Russell, B. - A History of Western Philosophy: And Its Connection with Political and Social Circumstances from the Earliest Times to the Present Day

In all history, nothing is so surprising or so difficult to account for as the sudden rise of civilization in Greece. Much of what makes civilization had already existed for thousands of years in Egypt and in Mesopotamia, and had spread thence to neighbouring countries. But certain elements had been lacking until the Greeks supplied them. What they achieved in art and literature is familiar to everybody, but what they did in the purely intellectual realm is even more exceptional.