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.