There are things which seem incredible to most men who have not studied Mathematics.

Archimedes to Eratosthenes greeting. ... certain things first became clear to me by a mechanical method, although they had to be demonstrated by geometry afterwards because their investigation by the said method did not furnish an actual demonstration. But it is of course easier, when we have previously acquired by the method, some knowledge of the questions, to supply the proof than it is to find it without any previous knowledge.

Give me but a firm spot on which to stand, and I shall move the earth.

The perimeter of the earth is about 3,000,000 stadia and not greater.

Man has always learned from the past. After all, you can't learn history in reverse!

Having been the discoverer of many splendid things, he is said to have asked his friends and relations that, after his death, they should place on his tomb a cylinder enclosing a sphere, writing on it the proportion of the containing solid to that which is contained.

Give me a place to stand, and a lever long enough, and I will move the world.