I have remarked various opinions among philosophers concerning the causes of sight and the nature of vision. The Stoics affirm the causes of sight to be an emission of radii from the eyes against those things which are capable of being seen, with an expansion at the same time of the air. But Epicurus thinks that there proceed from all bodies certain images of the bodies themselves, and that these impress themselves upon the eyes, and that thence arises the sense of sight. Plato is of opinion that a species of fire and light issues from the eyes, and that this, being united and continued either with the light of the sun or the light of some other fire, by its own, added to the external force, enables us to see whatever it meets and illuminates. But on these things it is not worth while to trifle further; and I recur to an opinion of the Neoptolemus of Ennius, whom I have before mentioned: he thinks that we should taste of philosophy, but not plunge in it over head and ears. Earliest Libraries Pisistratus the tyrant is said to have been the first who supplied books of the liberal sciences at Athens for public use. Afterwards the Athenians themselves with great care and pains increased their number; but all this multitude of books, Xerxes, when he obtained possession of Athens and burned the whole of the city except the citadel, seized and carried away to Persia. But King Seleucus, who was called Nicanor, many years afterwards, was careful that all of them should be again carried back to Athens. A prodigious number of books were in succeeding times collected by the Ptolemies in Egypt, to the amount of near seven hundred thousand volumes. But in the first Alexandrine war the whole library, during the plunder of the city, was destroyed by fire; not by any concerted design, but accidentally by the auxiliary soldiers. Realistic Acting There was an actor in Greece of great celebrity, superior to the rest in the grace and harmony of his voice and action. His name, it is said, was Polus, and he acted in the tragedies of the [Pg 6260] more eminent poets, with great knowledge and accuracy. This Polus lost by death his only and beloved son. When he had sufficiently indulged his natural grief, he returned to his employment. Being at this time to act the 'Electra' of Sophocles at Athens, it was his part to carry an urn as containing the bones of Orestes. The argument of the fable is so imagined that Electra, who is presumed to carry the relics of her brother, laments and commiserates his end, who is believed to have died a violent death. Polus, therefore, clad in the mourning habit of Electra, took from the tomb the bones and urn of his son, and as if embracing Orestes, filled the place, not with the image and imitation, but with the sighs and lamentations of unfeigned sorrow. Therefore, when a fable seemed to be represented, real grief was displayed. The Athlete's End