INFLUENCE OF THE ROMAN EMPIRE. 183 



inferior to the philosophically combining Theophrastes, while 

 the delicacy of his manner of dissecting, and the extent of his 

 physiological discoveries, place Galen, who extended his ob- 

 eervations to various genera of animals, " very nearly as high 

 as Aristotle, and, in some respects, even above him." This 

 judgment embodies the views of Cuvier.* 



Besides Dioscorides and Galen, our attention is called to a 

 third and great name that of Ptolemy. I do not mention 

 him here as an astronomical systematizer or as a geographer, 

 but as an experimental physicist, who measured refraction, 

 and who may, therefore, be regarded as the founder of an im- 

 portant branch of optical science, although his incontestable 

 claim to this title has been but recently admitted.! How- 

 ever important were the advances made in the sphere of or- 

 ganic life and in the general views of comparative zootomy, 

 our attention is yet more forcibly arrested by those physical 

 experiments on the passage of a ray of light, which, preceding 

 the period of the Arabs by an interval of five hundred years, 

 mark the first step in a newly-opened course, and the earliest 

 indication of a striving toward the establishment of mathe- 

 matical physics. 



The distinguished men whom we have already named as 

 shedding a scientific luster on the age of the imperial rulers 

 of Rome were all of Greek origin. The profound arithmeti- 

 cian and algebraist Diophantus (who was still unacquainted 

 with the use of symbols) belonged to a later period. J Amid 

 the different directions presented by intellectual cultivation in 

 the Roman empire, the palm of superiority remained with the 

 Hellenic races, as the older and more happily-organized peo- 



* Cuvier, Hist, des Sciences Naturelles, t. i., p. 312-328. 



t Liber Ptholemei de Opticis sive Aspectibus ; a rare manuscript of the 

 Royal Library at Paris (No. 7310), which I examined on the occasion of 

 discovering a remarkable passage on the refraction of rays in Sextus Em- 

 piricus (adversus Astrologos, lib. v., p. 351, Fabr.). The extracts which 

 1 made from the Paris manuscript in 1811 (therefore before Delambre 

 and Venturi) will be found in the introduction to my Recueil d' Obser- 

 vations Astronomiques, t. i., p. Ixv.-lxx. The Greek original has not been 

 preserved to us, and we have only a Latin translation of two Arabic 

 manuscripts of Ptolemy's Optics. The name of the Latin translator 

 was Amiracus Eugenius, Siculus. Compare Venturi, Comment, sopra la 

 Storia e le Teorie dell' Ottica, Bologna, 1814, p. 227 ; Delambre, Hist, 

 de V Astronomic Ancienne, 1817, t. i., p. 61, and t. ii., p. 410-432. 



t Letronne shows, from the occun'ence of the fanatical murder of 

 the daughter of Theon of Alexandria, that the much-contested epoch of 

 Diophantus can not be placed later than the year 389 (Sur I'Origine 

 Grecque des Zodiaques pr6tendus Egyptiens, 1837, p. 26). 



