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

Eureka! (I have found it!).

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

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

Equal weights at equal distances are in equilibrium and equal weights at unequal distances are not in equilibrium but incline towards the weight which is at the greater distance.

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

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