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!

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

Mathematics reveals its secrets only to those who approach it with pure love, for its own beauty.

How many theorems in geometry which have seemed at first impracticable are in time successfully worked out!

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