Give me a lever long enough and a fulcrum on which to place it, and I shall move the world.
How many theorems in geometry which have seemed at first impracticable are in time successfully worked out!
Those who claim to discover everything but produce no proofs of the same may be confuted as having actually pretended to discover the impossible.
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.
If two equal weights have not the same centre of gravity, the centre of gravity of both taken together is at the middle point of the line joining their centres of gravity.
Two magnitudes whether commensurable or incommensurable, balance at distances reciprocally proportional to the magnitudes.
The centre of gravity of any parallelogram lies on the straight line joining the middle points of opposite sides.
The centre of gravity of a parallelogram is the point of intersection of its diagonals.
In any triangle the centre of gravity lies on the straight line joining any angle to the middle point of the opposite side.