BOOK I. THE ROMAN EMPIRE

FOREWORD
A TRIO of great names, Pliny, Galen, and Ptolemy, stand out A trio of above all others in the history of science under the Roman names. Empire. In the use or criticism which they make of earlier writers and investigators they are also our chief sources for the science of the preceding Hellenistic period. By their voluminousness, their generous scope in ground covered, and their broad, liberal, personal outlooks, they have painted, in colors for the most part imperishable, extensive canvasses of the scientific spirit and acquisitions of their own time. Pliny pursued politics and literature as well as natural sci- ence; Ptolemy was at once mathematician, astronomer, physicist, and geographer; Galen knew philosophy as well as medicine. The two latter men, moreover, made original contributions of their own of the very first order to scientific knowledge and method. It is characteristic of the homo- geneous and widespread culture of the Roman Empire that these three representatives of different, although overlap- ping, fields of science were natives of the three continents that enclose the Mediterranean Sea. Pliny was bom at Como where Italy verges on transalpine lands ; Ptolemy, born some- where in Egypt, did his work at Alexandria; Galen came from Pergamum in Asia Minor. Finally, these men were, after Aristotle, the three ancient scientists who directly or indirectly most powerfully influenced the middle ages. Thus they illuminate past, present, and future.
We shall therefore open the present section of our in- plan of vestigation by considering in turn chronologically, Pliny, Ptolemy, and Galen, coupling, however, with our considera- tion of Ptolemy the work of Seneca on Natural Questions
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this section.
40 FOREWORD
which shows the same combination of natural science and natural divination. Next we shall consider some representa- tives of ancient applied science and its relations to magic, and the more miscellaneous writings of Plutarch, Apuleius, and Philostratus's Life of Apollonius of Tyana. From the hos- pitable attitude toward magic and occult science displayed by these last writers we sha'' then turn back again to consider some examples of literary and philosophical attacks upon superstition, before proceeding lastly to spurious mystic writings of the Roman Empire, Neo-Platonism and its re- lations to astrology and theurgy, and the works of Aelian, Solinus, and Horapollo.