The proof of very ancient communication between Greece and India is quite clear, both by way of Persia and Egypt, and we find that the Greeks, who were in the habit of calling all other nations barbarians, speak constantly with respect of the gymnosophists--called “Sapientes Indi” by Pliny. We read also of the Greek philosophers constantly travelling eastward in search of knowledge, and on their return setting up new schools of thought. Thales, it is affirmed, travelled in Egypt and Asia during the sixth century B.C., and it is said of him that he returned to Miletus, and transported that vast stock of learning which he had acquired into his own country. He is generally considered as the first of the Greek philosophers. Strabo says of him that he was the first of the Grecian philosophers who made inquiry into natural causes and the mathematics. The doctrine of Thales, that water was the first elementary principle, is exactly that of the ancient Hindoos, who held that water was the first element, and the first work of the creative power. This idea was not completely exploded even up till the 18th century. We find Van Helmont affirming that all metals, and even rocks, may be resolved into water; and Lavoisier, so lately as 1770, thought it worth while to communicate an elaborate paper “On the nature of water and the experiments by which it has been attempted to prove the possibility of converting it into earth.” Pythagoras, perhaps the greatest of all Greek philosophers, it is known, travelled very widely, spending no less than twenty-two years in Egypt. He also spent some considerable time at Babylon, and was taught the lore of the Magi. In the famous satire of Lucian on the philosophic quackery of his day (about 120 A.D.), “The Sale of the Philosophers,” we have a most interesting account of the system of Pythagoras. _Scene--A Slave Mart. _Jupiter_, _Mercury_, _philosophers_, in the garb of slaves, for sale. Audience of buyers._ _Jupiter._--Now, you arrange the benches, and get the place ready for the company. You bring out the goods and set them in a row; but trim them up a little first, and make them look their best, to attract as many customers as possible. You, Mercury, must put up the lots, and bid all comers welcome to the sale. Gentlemen,--We are here going to offer you philosophical systems of all kinds, and of the most varied and ingenious description. If any gentleman happens to be short of ready money he can give his security for the amount, and pay next year. _Mercury (to Jupiter)._--There are a great many come; so we had best begin at once, and not keep them waiting. _Jupiter._--Begin the sale, then. _Mercury._--Whom shall we put up first? _Jupiter._--This fellow with the long hair--the Ionian. He’s rather an imposing personage. _Mercury._--You, Pythagoras, step out, and show yourself to the company. _Jupiter._--Put him up.