CHAPTER III

MILTON'S ASTRONOMICAL KNOWLEDGE


It would be reasonable to imagine that Milton's knowledge of astronomy
was comprehensive and accurate, and superior to that possessed by most
scientific men of his age. His scholarly attainments, his familiarity
with ancient history and philosophy, his profound learning, and the
universality of his general knowledge, would lead one to conclude that
the science which treats of the mechanism of the heavens, and especially
the observational part of it--which at all times has been a source of
inspiration to poets of every degree of excellence--was to him a study
of absorbing interest, and one calculated to make a deep impression upon
his devoutly poetical mind. The serious character of Milton's verse, and
the reverent manner in which celestial incidents and objects are
described in it, impress one with the belief that his contemplation of
the heavens, and of the orbs that roll and shine in the firmament
overhead, afforded him much enjoyment and meditative delight. For no
poet, in ancient or in modern times, has introduced into his writings
with such frequency, or with such pleasing effect, so many passages
descriptive of the beauty and grandeur of the heavens. No other poet,
by the creative effort of his imagination, has soared to such a height;
nor has he ever been excelled in his descriptions of the celestial orbs,
and of the beautiful phenomena associated with their different motions.

In his minor poems, which were composed during his residence at Horton,
a charming rural retreat in Buckinghamshire, where the freshness and
varied beauty of the landscape and the attractive aspects of the
midnight sky were ever before him, we find enchanting descriptions of
celestial objects, and especially of those orbs which, by their
brilliancy and lustre, have always commanded the admiration of mankind.

For example, in 'L'Allegro' there are the following lines:--

Right against the eastern gate
Where the great Sun begins his state,
Robed in flames and amber light,
The clouds in thousand liveries dight;

and in 'Il Penseroso'--

To behold the wandering Moon,
Riding near her highest noon,
Like one that had been led astray
Through the heaven's wide pathless way,
And oft as if her head she bowed,
Stooping through a fleecy cloud.

In the happy choice of his theme, and by the comprehensive manner in
which he has treated it, Milton has been enabled by his poetic genius to
give to the world in his 'Paradise Lost' a poem which, for sublimity of
thought, loftiness of imagination, and beauty of expression in metrical
verse, is unsurpassed in any language.

It is, however, our intention to deal only with those passages in the
poem in which allusion is made to the heavenly bodies, and to incidents
and occurrences associated with astronomical phenomena. In the
exposition and illustration of these it has been considered desirable to
adopt the following general classification:--

1. To ascertain the extent of Milton's astronomical knowledge.

2. To describe the starry heavens and the celestial objects mentioned in
'Paradise Lost.'

3. To exemplify the use which Milton has made of astronomy in the
exercise of his imaginative and descriptive powers.

In the earlier half of the seventeenth century the Ptolemaic theory--by
which it was believed that the Earth was the immovable centre of the
universe, and that round it all the heavenly bodies completed a diurnal
revolution--still retained its ascendency over the minds of men of
learning and science, and all the doctrines associated with this ancient
astronomical creed were still religiously upheld by the educated classes
among the peoples inhabiting the different civilised regions of the
globe. The Copernican theory--by which the Sun is assigned the central
position in our system, with the Earth and planets revolving in orbits
round him--obtained the support of a few persons of advanced views and
high scientific attainments, but its doctrines had not yet seriously
threatened the supremacy of the older system. Though upwards of one
hundred years had elapsed since the death of Copernicus, yet the
doctrines associated with the system of which he was the founder were
but very tardily adopted up to this time. There were several reasons
which accounted for this. The Copernican system was at first imperfect
in its details, and included several of the Ptolemaic, doctrines which
rendered it less intelligible, and retarded its acceptance by persons
who would otherwise have been inclined to adopt it. Copernicus believed
that the planets travelled round the Sun in circular paths. This
necessitated the retention of cycles and epicycles, which gave rise to
much confusion; nor was it until Kepler made his great discovery of the
ellipticity of the planetary orbits that they were eliminated from the
system.

As the Ptolemaic system of the universe held complete sway over the
minds of men for upwards of twenty centuries, it was difficult to
persuade many persons to renounce the astronomical beliefs to which they
were so firmly attached, in favour of those of any other system; so that
the overthrow of this venerable theory required a lengthened period of
time for its accomplishment.

It was thus in his earlier years, when Milton devoted his time to the
study of literature and philosophy, which he read extensively when
pursuing his academic career at Christ's College, Cambridge, and
afterwards at Horton, where he spent several years in acquiring a more
proficient knowledge of the literary, scientific, and philosophical
writings of the age, that he found the beliefs associated with the
Ptolemaic theory adopted without doubt or hesitation by the numerous
authors whose works he perused. His knowledge of Italian enabled him to
become familiar with Dante--one of his favourite authors, whose poetical
writings were deeply read by him, and who, in the elaboration of his
poem, the 'Divina Commedia,' included the entire Ptolemaic cosmology.

In England the Copernican theory had few supporters, and the majority of
those who represented the intellect and learning of the country still
retained their adherence to the old form of astronomical belief. We
therefore find that Milton followed the traditional way of thinking by
adopting the views associated with the Ptolemaic theory.

According to the Ptolemaic system, the Earth was regarded as the
immovable centre of the universe, and surrounding it were ten
crystalline spheres, or heavens, arranged in concentric circles, the
larger spheres enclosing the smaller ones; and within those was situated
the cosmos, or mundane universe, usually described as 'the Heavens and
the Earth.' To each of the first seven spheres there was attached a
heavenly body, which was carried round the Earth by the revolution of
the crystalline.

1st sphere: that of the Moon.

2nd sphere: that of the planet Mercury.

3rd sphere: that of the planet Venus.

4th sphere: that of the Sun; regarded as a planet.

5th sphere: that of the planet Mars.

6th sphere: that of the planet Jupiter.

7th sphere: that of the planet Saturn.

8th sphere: that of the fixed stars.

[Illustration: FIG. 1]

The eighth sphere included all the fixed stars, and was called the
firmament, because it was believed to impart steadiness to the inner
spheres, and, by its diurnal revolution, to carry them round the Earth,
causing the change of day and night.

The separate motions of the spheres, revolving with different
velocities, and at different angles to each other, accounted for the
astronomical phenomena associated with the orbs attached to each.
According to Ptolemy's scheme, the eighth sphere formed the outermost
boundary of the universe; but later astronomers added to this system two
other spheres--a _ninth_, called the _Crystalline_, which caused
Precession of the Equinoxes; and a _tenth_, called the _Primum Mobile_,
or First Moved, which brought about the alternation of day and night, by
carrying all the other spheres round the Earth once in every twenty-four
hours. The Primum Mobile enclosed, as if in a shell, all the other
spheres, in which was included the created universe, and, although of
vast dimensions, its conception did not overwhelm the mind in the same
manner that the effort to comprehend infinitude does.

Beyond this last sphere there was believed to exist a boundless,
uncircumscribed region, of immeasurable extent, called the Empyrean, or
Heaven of Heavens, the incorruptible abode of the Deity, the place of
eternal mysteries, which the comprehension of man was unable to fathom,
and of which it was impossible for his mind to form any conception. Such
were the imaginative beliefs upon which this ancient astronomical theory
was founded, that for a period of upwards of two thousand years held
undisputed sway over the minds of men, and exercised during that time a
predominating influence upon the imagination, thoughts, and conceptions
of all those who devoted themselves to literature, science, and art. Of
the truthfulness of this assertion there is ample evidence in the
poetical, philosophical, and historical writings of ancient authors,
whose ideas and conceptions regarding the created universe were limited
and circumscribed by this form of astronomical belief. In the works of
more recent writers we find that it continued to assert its influence;
and among our English poets, from Chaucer down to Shakespeare, there are
numerous references to the natural phenomena associated with this
system, and most frequently expressed by poetical allusions to 'the
music of the spheres.'

The ideas associated with the Ptolemaic theory were gratifying to the
pride and vanity of man, who could regard with complacency the paramount
importance of the globe which he inhabited, and of which he was the
absolute ruler, fixed in the centre of the universe, and surrounded by
ten revolving spheres, that carried along with them in their circuit all
other celestial bodies--Sun, Moon, and stars, which would appear to have
been created for his delectation, and for the purpose of ministering to
his requirements. But when the Copernican theory became better
understood, and especially after the discovery of the law of universal
gravitation, this venerable system of the universe, based upon a pile of
unreasonable and false hypotheses, after an existence of over twenty
centuries, sank into oblivion, and was no more heard of.

Milton's Ptolemaism is apparent in some of his shorter pieces, and also
in his minor poems, 'Arcades' and 'Comus.' His 'Ode on the Nativity' is
written in conformity with this belief, and the expression,

Ring out ye crystal spheres,

indicates a poetical allusion to this theory. But as Milton grew older
his Ptolemaism became greatly modified, and there are good reasons for
believing that in his latter years he renounced it entirely in favour of
Copernicanism. When on his continental tour in 1638, he made the
acquaintance of eminent men who held views different from those with
which he was familiar; and in his interview with Galileo at Arcetri, the
aged astronomer may have impressed upon his mind the superiority of the
Copernican theory, in accounting for the occurrence of celestial
phenomena, as compared with the Ptolemaic.

On his return to England from the Continent, Milton took up his
residence in London, and lived in apartments in a house in St. Bride's
Churchyard. Having no regular vocation, and not wishing to be dependent
upon his father, he undertook the education of his two nephews, John and
Edward Phillips, aged nine and ten years respectively. From St. Bride's
Churchyard he removed to a larger house in Aldersgate, where he received
as pupils the sons of some of his most intimate acquaintances. In the
list of subjects which Milton selected for the purpose of imparting
instruction to those youths he included astronomy and mathematics,
which formed part of the curriculum of this educational establishment.
The text-book from which he taught his nephews and other pupils
astronomy was called 'De Sphaera Mundi,' a work written by Joannes
Sacrobasco (John Holywood) in the thirteenth century. This book was an
epitome of Ptolemy's 'Almagest,' and therefore entirely Ptolemaic in its
teaching. It enjoyed great popularity during the Middle Ages, and is
reported to have gone through as many as forty editions.

The selection of astronomy as one of the subjects in which Milton
instructed his pupils affords us evidence that he must have devoted
considerable time and attention to acquiring a knowledge of the facts
and details associated with the study of the science. In the attainment
of this he had to depend upon his own exertions and the assistance
derived from astronomical books; for at this time astronomy received no
recognition as a branch of study at any of the universities; and in
Britain the science attracted less attention than on the Continent,
where the genius of Kepler and Galileo elevated it to a position of
national importance.

We shall find as we proceed that Milton's knowledge of astronomy was
comprehensive and accurate; that he was familiar with the astronomical
reasons by which many natural phenomena which occur around us can be
explained; and that he understood many of the details of the science
which are unknown to ordinary observers of the heavens.

It is remarkable how largely astronomy enters into the composition of
'Paradise Lost,' and we doubt if any author could have written such a
poem without possessing a knowledge of the heavens and of the celestial
orbs such as can only be attained by a proficient and intimate
acquaintance with this science.

The arguments in favour of or against the Ptolemaic and Copernican
theories were well known to Milton, even as regards their minute
details; and in Book viii. he introduces a scientific discussion based
upon the respective merits of those theories. The configuration of the
celestial and terrestrial spheres, and the great circles by which they
are circumscribed, he also knew. The causes which bring about the change
of the seasons; the obliquity of the ecliptic; the zodiacal
constellations through which the Sun travels, and the periods of the
year in which he occupies them, are embraced in Milton's knowledge of
the science of astronomy. The motions of the Earth, including the
Precession of the Equinoxes; the number and distinctive appearances of
the planets, their direct and retrograde courses, and their satellites,
are also described by him. The constellations, and their relative
positions on the celestial sphere; the principal stars, star-groups, and
clusters, and the Galaxy, testify to Milton's knowledge of astronomy,
and to the use which he has made of the science in the elaboration of
his poem.

The names of fourteen of the constellations are mentioned in 'Paradise
Lost.' These, when arranged alphabetically, read as follows:--

Andromeda, Aries, Astrea, Centaurus, Cancer, Capricornus, Gemini, Leo,
Libra, Ophiuchus, Orion, Scorpio, Taurus, and Virgo. Milton's allusions
to the zodiacal constellations are chiefly associated with his
description of the Sun's path in the heavens; but with the celestial
sign Libra (the _Scales_) he has introduced a lofty and poetical
conception of the means by which the Creator made known His will when
there arose a contention between Gabriel and Satan on his discovery in
Paradise.

The Eternal, to prevent such horrid fray,
Hung forth in Heaven his golden scales, yet seen
Betwixt Astrea[6] and the Scorpion sign,
Wherein all things created first he weighed,
The pendulous round Earth with balanced air
In counterpoise, now ponders all events,
Battles and realms. In these he put two weights,
The sequel each of parting and of fight:
The latter quick up flew, and kicked the beam.--iv. 996-1004.

Orion, the finest constellation in the heavens, did not escape Milton's
observation, and there is one allusion to it in his poem. It arrives on
the meridian in winter, where it is conspicuous as a brilliant
assemblage of stars, and represents an armed giant, or hunter, holding a
massive club in his right hand, and having a shield of lion's hide on
his left arm. A triple-gemmed belt encircles his waist, from which is
suspended a glittering sword, tipped with a bright star. The two
brilliants Betelgeux and Bellatrix form the giant's shoulders, and the
bright star Rigel marks the position of his advanced foot. The rising of
Orion was believed to be accompanied by stormy and tempestuous weather.
Milton alludes to this in the following lines:--

When with fierce winds Orion armed
Hath vexed the Red Sea coast, whose waves o'erthrew
Busiris and his Memphian chivalry.--i. 305-7.

Andromeda is described as being borne by Aries, and in 'Ophiuchus huge'
Milton locates a comet which extends the whole length of the
constellation. It is evident that Milton possessed a precise knowledge
of the configuration and size of the constellations, and of the
positions which they occupy relatively to each other on the celestial
sphere.

Though Milton was conversant with the Copernican theory, and entertained
a conviction of its accuracy and truthfulness, and doubtless recognised
the superiority of this system, which, besides conveying to the mind a
nobler conception of the universe and of the solar system--though it
diminished the importance of the Earth as a member of it--was capable of
explaining the occurrence of celestial phenomena in a manner more
satisfactory than could be arrived at by the Ptolemaic theory.
Notwithstanding this, he selected the Ptolemaic cosmology as the
scientific basis upon which he constructed his 'Paradise Lost,' and in
its elaboration adhered with marked fidelity to this system. There were
many reasons why Milton, in the composition of an imaginative poem,
should have chosen the Ptolemaic system of the universe rather than the
Copernican. This form of astronomical belief was adopted by all the
authors whose works he perused and studied in his younger days,
including his favourite poet, Dante; and his own poetic imaginings, as
indicated by his early poems, were in harmony with the doctrines of this
astronomical creed, a long acquaintance with which had, without doubt,
influenced his mind in its favour. This system of revolving spheres,
with the steadfast Earth at its centre, and the whole enclosed by the
Primum Mobile, constituted a more attractive and picturesque object for
poetic description than the simple and uncircumscribed arrangement of
the universe expressed by the Copernican theory. It also afforded him an
opportunity of localising those regions of space in which the chief
incidents in his poem are described--viz. HEAVEN, or THE EMPYREAN,
CHAOS, HELL, and the MUNDANE UNIVERSE. Milton's Ptolemaism, with its
adjuncts, may be understood by the following:

All that portion of space above the newly created universe, and beyond
the Primum Mobile, was known as HEAVEN, or THE EMPYREAN--a region of
light, of glory, and of happiness; the dwelling-place of the Deity, Who,
though omnipresent, here visibly revealed Himself to all the multitude
of angels whom He created, and who surrounded his throne in adoration
and worship.

Underneath the universe there existed a vast region of similar
dimensions to the Empyrean, called CHAOS, which was occupied by the
embryo elements of matter, that with incessant turmoil and confusion
warred with each other for supremacy--a wild abyss--

The womb of Nature and perhaps her grave.--ii. 911.

The lower portion of this region was divided off from the remainder, and
embraced the locality known as HELL--the place of torment, where the
rebellious angels were driven and shut in after their expulsion from
Heaven.

As far removed from God and light of Heaven
As from the centre thrice to the utmost pole.--i. 73-74.

The NEW UNIVERSE, which included the Earth and all the orbs of the
firmament known as the Starry Heavens, was created out of Chaos, and
hung, as if suspended by a golden chain, from the Empyrean above; and
although its magnitude and dimensions were inconceivable, yet, according
to the Ptolemaic theory, it was enclosed by the tenth sphere or Primum
Mobile.

By this partitioning of space Milton was able to contrive a system which
fulfilled the requirements of his great poem.

The annexed diagram explains the relative positions of the different
regions into which space was divided.

Though there are traces of Copernicanism found in 'Paradise Lost,' yet
Milton has very faithfully adhered to the Ptolemaic mechanism and
nomenclature throughout his poem.

In his description of the Creation, the Earth is formed first, then the
Sun, followed by the Moon, and afterwards the stars, all of which are
described as being in motion round the Earth. Allusion is also made to
this ancient system in several prominent passages, and in the following
lines there is a distinct reference to the various revolving spheres.

[Illustration: FIG. 2]

They pass the planets seven, and pass the fixed,
And that crystalline sphere whose balance weighs
The trepidation talked, and that first moved.--iii. 481-83.

The seven planetary spheres are first mentioned; then the eighth sphere,
or that of the fixed stars; then the ninth, or crystalline, which was
believed to cause a shaking, or trepidation, to account for certain
irregularities in the motions of the stars; and, lastly, the tenth
sphere, or Primum Mobile, called the 'first moved' because it set the
other spheres in motion.

To an uninstructed observer, the apparent motion of the heavenly bodies
round the Earth would naturally lead him to conclude that, of the two
theories, the Ptolemaic was the correct one. We therefore find that
Milton adopted the system most in accord with the knowledge and
intelligence possessed by the persons portrayed by him in his poem; and
in describing the natural phenomena witnessed in the heavens by our
first parents, he adheres to the doctrines of the Ptolemaic system, as
being most in harmony with the simple and primitive conceptions of those
created beings.

To their upward gaze, the orbs of heaven appeared to be in ceaseless
motion; the solid Earth, upon which they stood, was alone immovable and
at rest. Day after day they observed the Sun pursue his steadfast course
with unerring regularity: his rising in the east, accompanied by the
rosy hues of morn; his meridian splendour, and his sinking in the west,
tinting in colours of purple and gold inimitable the fleecy clouds
floating in the azure sky, as he bids farewell for a time to scenes of
life and happiness, rejoicing in the light and warmth of his
all-cheering beams. With the advent of night they beheld the Moon, now
increasing, now waning, pursue her irregular path, also to disappear in
the west; whilst, like the bands of an army marshalled in loose array,
the constellations of glittering stars, with stately motion, traversed
their nocturnal arcs, circling the pole of the heavens.

By referring to Book viii., 15-175, we find an account of an interesting
scientific discussion, or conversation, between Adam and Raphael
regarding the merits of the Ptolemaic and Copernican systems, and of the
relative importance and size of the heavenly bodies. By it we are
afforded an opportunity of learning how accurate and precise a knowledge
Milton possessed of both theories, and in what clear and perspicuous
language he expresses his arguments in favour of or against the
doctrines associated with each.

We may, with good reason, regard the views expressed by Adam as
representing Milton's own opinions, which were in conformity with the
Copernican theory; and in the Angel's reply, though of an undecided
character, we are able to perceive how aptly Milton describes the
erroneous conclusions upon which the Ptolemaic theory was based.

In this scientific discussion, it would seem rather strange that Adam,
the first of men, should have been capable of such philosophic
reasoning, propounding, as if by intuition, a theory upon which was
founded a system that had not been discovered until many centuries after
the time that astronomy became a science. By attributing to Adam such a
degree of intelligence and wisdom, the poet has taken a liberty which
enabled him to carry on this discussion in a manner befitting the
importance of the subject.

In the following lines Adam expresses to his Angel-guest, in forcible
and convincing language, his reasons in support of the Copernican
theory:--

When I behold this goodly frame, this World,
Of Heaven and Earth consisting, and compute
Their magnitudes--this Earth, a spot, a grain,
An atom, with the Firmament compared
And all her numbered stars, that seem to roll
Spaces incomprehensible (for such
Their distance argues, and their swift return
Diurnal) merely to officiate light
Round this opacous Earth, this punctual spot,
One day and night, in all her vast survey
Useless besides--reasoning, I oft admire,
How Nature, wise and frugal could commit
Such disproportions, with superfluous hand
So many nobler bodies to create,
Greater so manifold, to this one use,
For aught appears, and on their Orbs impose
Such restless revolution day by day
Repeated, while the sedentary Earth,
That better might with far less compass move,
Served by more noble than herself, attains
Her end without least motion, and receives,
As tribute, such a sumless journey brought
Of incorporeal speed, her warmth and light;
Speed, to describe whose swiftness number fails.--viii. 15-38.

We are enabled to perceive that Milton had formed a correct conception
of the magnitude and proportions of the universe, and also of the
relative size and importance of the Earth, which he describes as 'a
spot, a grain, an atom,' when compared with the surrounding heavens. He
expresses his surprise that all the stars of the firmament, whose
distances are so remote, and whose dimensions so greatly exceed those of
this globe, should in their diurnal revolution have 'such a sumless
journey of incorporeal speed imposed upon them' merely to officiate
light to the Earth, 'this punctual spot;' and reasoning, wonders how
Nature, wise and frugal in her ways, should commit such disproportions,
by adopting means so great to accomplish a result so small, when motion
imparted to the sedentary Earth would with greater ease produce the same
effect.

The inconceivable velocity with which it would be necessary for those
orbs to travel in order to accomplish a daily revolution round the Earth
might be described as almost spiritual, and beyond the power of
calculation by numbers.

The Angel, after listening to Adam's argument, expresses approval of his
desire to obtain knowledge, but answers him dubiously, and at the same
time criticises in a severe and adverse manner the Ptolemaic theory.

To ask or search I blame thee not; for Heaven
Is as the Book of God before thee set,
Wherein to read his wondrous works, and learn
His seasons, hours, or days, or months, or years.
This to attain, whether Heaven move or Earth,
Imports not, if thou reckon right; the rest
From Man or Angel the Great Architect
Did wisely to conceal, and not divulge
His secrets, to be scanned by them who ought
Rather admire. Or, if they list to try
Conjecture, he his fabric of the Heavens
Hath left to their disputes, perhaps to move
His laughter at their quaint opinions wide
Hereafter, when they come to model Heaven,
And calculate the stars; how they will wield
The mighty frame; how build, unbuild, contrive
To save appearances; how gird the Sphere
With Centric and Eccentric scribbled o'er
Cycle and Epicycle, Orb in Orb.--viii. 66-84.

When, with the advancement of science, astronomical observations were
made with greater accuracy, it was discovered that uniformity of motion
was not always maintained by those bodies which were believed to move in
circles round the Earth. It was observed that the Sun, when on one side
of his orbit, had an accelerated motion, as compared with the speed at
which he travelled when on the other side. The planets, also, appeared
to move with irregularity: sometimes a planet was observed to advance,
then become stationary, and afterwards affect a retrograde movement.
Those inequalities of motion could not be explained by means of the
revolution of crystalline spheres alone, but were accounted for by
imagining the existence of a small circle, or epicycle, whose centre
corresponded with a fixed point in the larger circle, or eccentric, as
it was called. This small circle revolved on its axis when carried round
with the larger one, and round it the planet also revolved, which when
situated in its outer portion would have a forward, and when in its
inner portion a retrograde, motion.

The theory of eccentrics and epicycles was sufficient for a time to
account for the inequalities of motion already described, and by this
means the Ptolemaic system was enabled to retain its ascendency for a
longer period than it otherwise would have done. But more recent
discoveries brought to light discrepancies and difficulties which were
explained away by adding epicycle to epicycle. This created a most
complicated entanglement, and hastened the downfall of a system which,
after an existence of many centuries, sank into oblivion, and is now
remembered as a belief of bygone ages.

The devices which the upholders of this system were compelled to adopt,
in order 'to save appearances,' with 'centric and eccentric,' cycle and
epicycle, 'orb in orb,' are in this manner appropriately described by
Milton, as indicating the confusion arising from a theory based upon
false hypotheses.

Continuing his reply, the Angel says:--

Already by thy reasoning this I guess,
Who art to lead thy offspring, and supposest
That bodies bright and greater should not serve
The less not bright, nor Heaven such journies run,
Earth sitting still, when she alone receives
The benefit. Consider, first, that great
Or bright infers not excellence. The Earth,
Though, in comparison of Heaven, so small,
Nor glistering, may of solid good contain
More plenty than the Sun that barren shines,
Whose virtue on itself works no effect,
But in the fruitful Earth; there first received,
His beams, inactive else, their vigour find,
Yet not to Earth are those bright luminaries
Officious, but to thee, Earth's habitant.
And, for the Heaven's wide circuit, let it speak
The Maker's high magnificence, who built
So spacious, and his line stretched out so far,
That Man may know he dwells not in his own--
An edifice too large for him to fill,
Lodged in a small partition; and the rest
Ordained for uses to his Lord best known,
The swiftness of those Circles attribute,
Though numberless, to his Omnipotence,
That to corporeal substances could add
Speed almost spiritual. Me thou think'st not slow,
Who since the morning-hour set out from Heaven
Where God resides, and ere midday arrived
In Eden--distance inexpressible
By numbers that have name. But this I urge,
Admitting motion in the Heavens, to show
Invalid that which thee to doubt it moved;
Not that I so affirm, though so it seem
To thee who hast thy dwelling here on Earth.
God, to remove his ways from human sense,
Placed Heaven from Earth so far, that earthly sight,
If it presume, might err in things too high,
And no advantage gain.--viii. 85-122.

Notwithstanding the Angel's severe criticism of the Ptolemaic system, he
does not unreservedly support the conclusions arrived at by Adam, but
endeavours to show that his reasoning may not be altogether correct. He
questions the validity of his argument that bodies of greater size and
brightness should not serve the smaller, though not bright, and that
heaven should move, while the Earth remained at rest. He argues that
great or bright infers not excellence, and that the Earth, though small,
may contain more virtue than the Sun, that 'barren shines,' whose beams
create no beneficial effect, except when directed on the fruitful
Earth. He reminds Adam that those bright luminaries minister not to the
Earth, but to himself, 'Earth's habitant,' and directs his attention to
the magnificence and extent of the surrounding universe, of which he
occupies but a small portion. The diurnal swiftness of the orbs that
move round the Earth he attributes to God's omnipotence, that to
material bodies 'could add speed almost spiritual.'

The Angel, after alluding to his rapid flight through space, suggests
that God placed heaven so far from Earth that man might not presume to
inquire into things which it would be of no advantage for him to know.
He then suddenly changes to the Copernican system, which he lucidly
describes in the following lines:--

What if the Sun
Be centre to the World, and other stars
By his attractive virtue and their own
Incited, dance about him various rounds?
Their wandering course, now high, now low, then hid,
Progressive, retrograde, or standing still,
In six thou seest; and what if, seventh to these
The planet Earth, so steadfast though she seem,
Insensibly three different motions move?
Which else to several spheres thou must ascribe,
Moved contrary with thwart obliquities,
Or save the Sun his labour, and that swift
Nocturnal and diurnal rhomb supposed
Invisible else above all stars, the wheel
Of day and night; which needs not thy belief,
If Earth, industrious of herself, fetch day
Travelling east, and with her part averse
From the Sun's beam meet night, her other part
Still luminous by his ray. What if that light,
Sent from her through the wide transpicuous air,
To the terrestrial Moon be as a star,
Enlightening her by day, as she by night
This Earth--reciprocal, if land be there,
Fields and inhabitants? Her spots thou seest
As clouds, and clouds may rain, and rain produce
Fruits in her softened soil, for some to eat
Allotted there; and other Suns, perhaps,
With their attendant Moons, thou wilt descry,
Communicating male and female light--
Which two great sexes animate the World,
Stored in each orb perhaps with some that live.
For such vast room in Nature unpossessed
By living soul, desert and desolate,
Only to shine, yet scarce to contribute
Each orb a glimpse of light, conveyed so far
Down to this habitable, which returns
Light back to them, is obvious to dispute.--viii. 122-58.

The Copernican theory, which is less complicated and more easily
understood than the Ptolemaic, is described by Milton with accuracy and
methodical skill.

The Sun having been assigned that central position in the system which
his magnitude and importance claim as his due, the planets circling in
orbits around him have their motions described in a manner indicative of
the precise knowledge which Milton acquired of this theory. At this time
the law of gravitation was unknown, and, although the ellipticity of the
orbits of the planets had been discovered by Kepler, the nature of the
motive force which guided and retained them in their paths still
remained a mystery. It was believed that the planets were whirled round
the Sun, as if by the action of magnetic fibres; a mutual attractive
influence having been supposed to exist between them and the orb,
similar to that of the opposite poles of magnets.

Milton alludes to this theory in the following lines:--

They, as they move
Their starry dance in numbers that compute
Days, months, and years, towards his all-cheering lamp
Turn swift their various motions, or are turned
By his magnetic beam.--iii. 579-83.

An important advance upon this theory was made by Horrox, who, in his
study of celestial dynamics, attributed the curvilineal motion of the
planets to the influence of two forces, one projective, the other
attractive. He illustrated this by observing the path described by a
stone when thrown obliquely into the air. He perceived that its motion
was governed by the impulse imparted to it by the hand, and also by the
attractive force of the Earth. Under these two influences, the stone
describes a graceful curve, and in its descent falls at the same angle
at which it rose. Hence arises the general law: 'When two spheres are
mutually attracted, and if not prevented by foreign influences, their
straight paths are deflected into curves concave to each other, and
corresponding with one of the sections of a cone, according to the
velocity of the revolving body. If the velocity with which the revolving
body is impelled be equal to what it would acquire by falling through
half the radius of a circle described from the centre of deflection, its
orbit will be circular; but if it be less than that quantity, its path
becomes elliptical.'

Newton afterwards embraced this law in his great principle of
gravitation, and demonstrated that the force which guides and retains
the Earth and planets in their orbits resides in the Sun. By the orb's
attractive influence a planet, after having received its first impulse,
is deflected from its original straight path, and bent towards that
luminary, and by the combined action of the projective and attractive
forces is made to describe an orbit which, if elliptical, has one of its
foci occupied by the Sun. So evenly balanced are those two forces, that
one is unable to gain any permanent ascendency over the other, and
consequently the planet traverses its orbit with unerring regularity,
and, if undisturbed by external influences, will continue in its path
for all time.

Milton describes the position of the planets in the sky as--

Now high, now low, then hid;

and their motions--

Progressive, retrograde, or standing still.

It is evident that Milton was familiar with the apparently irregular
paths pursued by the planets when observed from the Earth. He knew of
their stationary points, and also the backward loopings traced out by
them on the surface of the sphere.

If observed from the Sun, all the planets would be seen to follow their
true paths round that body; their motion would invariably lie in the
same direction, and any variation in their speed as they approached
perihelion or aphelion would be real. But the planets, when observed
from the Earth, which is itself in motion, appear to move irregularly.
Sometimes they remain stationary for a brief period, and, instead of
progressing onward, affect a retrograde movement. This irregularity of
motion is only apparent, and can be explained as a result of the
combined motions of the Earth and planets, which are travelling together
round the Sun with different velocities, and in orbits of unequal
magnitude.

In his allusion to the Copernican system the 'planet' 'Earth' is
described by Milton as seventh. This is not strictly accurate, as only
five planets were known--viz. Mercury, Venus, Mars, Jupiter, and Saturn;
but to make up the number Milton has included the Moon, which may be
regarded as the Earth's planet.

The three motions ascribed to the Earth are--(1) The diurnal rotation on
her axis; (2) her annual revolution round the Sun; (3) Precession of the
Equinoxes.

The rotation of the Earth on her axis may be likened to the spinning
motion of a top, and is the cause of the alternation of day and night.
This rotatory motion is sustained with such exact precision that, during
the past 2,000 years, it has been impossible to detect the minutest
difference in the time in which the Earth accomplishes a revolution on
her axis, and therefore the length of the sidereal day, which is 3
minutes 56 seconds shorter than the mean solar day, is invariable. In
this motion of the Earth we have a time-measuring unit which may be
regarded as absolutely correct.

The Earth completes a revolution of her orbit in 365-1/4 days. In this
period of time she accomplishes a journey of 580 millions of miles,
travelling at the average rate of 66,000 miles an hour. The change of
the seasons, and the lengthening and shortening of the day, are natural
phenomena, which occur as a consequence of the Earth's annual revolution
round the Sun. Precession is a retrograde or westerly motion of the
equinoctial points, caused by the attraction of the Sun, Moon, and
planets on the spheroidal figure of the Earth. By this movement the
poles of the Earth are made to describe a circular path in that part of
the heavens to which they point; so that, after the lapse of many years,
the star which is known as the Pole Star will not occupy the position
indicated by its name, but will be situated at a considerable distance
from the pole. These motions, Milton says, unless attributed to the
Earth, must be ascribed to several spheres crossing and thwarting each
other obliquely; but the Earth, by rotating from west to east, will of
herself fetch day, her other half, averted from the Sun's rays, being
enveloped in night. Thus saving the Sun his labour, and the 'primum
mobile,' 'that swift nocturnal and diurnal rhomb,' which carried all the
lower spheres along with it, and brought about the change of day and
night.

Milton's allusion to the occurrence of natural phenomena in the Moon
similar to those which happen on the Earth is in keeping with the
opinions entertained regarding our satellite, Galileo having imagined
that he discovered with his telescope continents and seas on the lunar
surface, which led to the belief that the Moon was the abode of
intelligent life.

... and other suns, perhaps,
With their attendant moons, thou wilt descry
Communicating male and female light.--viii. 148-50.

Milton in these lines refers to Jupiter and Saturn, and their
satellites, which had been recently discovered; those of the former by
Galileo, and four of those of the latter by Cassini. The existence of
male and female light was an idea entertained by the ancients, and which
is mentioned by Pliny. The Sun was regarded as a masculine star, and the
Moon as feminine; the light emanating from each being similarly
distinguished, and possessing different properties.

Milton supposes that, as the Earth receives light from the stars, she
returns light back to them. But in his time little was known about the
stars, nor was it ascertained how distant they are.

The Angel, in bringing to a conclusion his conversation with Adam, deems
it unadvisable to vouchsafe him a decisive reply to his inquiry
regarding the motions of celestial bodies, and in the following lines
gives a beautifully poetical summary of this elevated and philosophic
discussion:--

But whether thus these things, or whether not,
Whether the Sun, predominant in Heaven,
Rise on the Earth, or Earth rise on the Sun;
He from the east his flaming round begin,
Or she from west her silent course advance
With inoffensive pace that spinning sleeps
On her soft axle, whilst she paces even,
And bears thee soft with the smooth air along--
Solicit not thy thoughts with matters hid.--viii. 159-67.

In this scientific discourse between Adam and Raphael, in which they
discuss the structural arrangement of the heavens and the motions of
celestial bodies, we are afforded an opportunity of learning what exact
and comprehensive knowledge Milton possessed of both the Ptolemaic and
Copernican theories. The concise and accurate manner in which he
describes the doctrines belonging to each system indicates that he must
have devoted considerable time and attention to making himself master of
the details associated with both theories, which in his time were the
cause of much controversy and discussion among philosophers and men of
science.

The Ptolemaic system, with its crystalline spheres revolving round the
Earth, the addition to those of cycles and epicycles, and the heaping of
them upon each other, in order to account for phenomena associated with
the motions of celestial bodies, are concisely and accurately described.

The unreasonableness of this theory, when compared with the Copernican,
is clearly delineated by Milton where Adam is made to express his views
with regard to motion in the heavens. His argument, declared in logical
and persuasive language, demonstrates how contrary to reason it would be
to imagine that the entire heavens should revolve round the Earth to
bring about a result which could be more easily attained by imparting
motion to the Earth herself. The inconceivable velocity with which it
would be necessary for the celestial orbs to travel in order to
accomplish their daily revolution is described by him as opposed to all
reason, and entailing upon them a journey which it would be impossible
for material bodies to perform. None the less accurate is Milton's
description of the Copernican system. He describes the Sun as occupying
that position in the system which his magnitude and supreme importance
claim as his sole right, having the planets with their satellites,

That from his lordly eye keep distance due.--iii. 578,

circling in majestic orbits around him, acknowledging his controlling
power, and bending to his firm but gentle sway. Their positions, their
paths, and their motions, real and apparent, are described in flowing
and harmonious verse.