Many people believe that the grains of sand are infinite in multitude ... Others think that although their number is not without limit, no number can ever be named which will be greater than the number of grains of sand. But I shall try to prove to you that among the numbers which I have named there are those which exceed the number of grains in a heap of sand the size not only of the earth, but even of the universe

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

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

Those who claim to discover everything but produce no proofs of the same may be confuted as having actually pretended to discover the impossible.

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.

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

Eureka! [I have found it!] On discovery of a method to test the purity of gold.