"Immeasurably superior to Aristotle as a student of mechanics is Archimedes. He is the true originator of mechanics as a science. To him we owe the theory of the centre of gravity (centroid) and of the lever. In his Equiponderance of Planes [On the Equilibrium of Planes] he starts with the axiom that equal weights acting at equal distances on opposite sides of a pivot are in equilibrium, and then endeavours to establish the principle that "in the lever unequal weights are in equilibrium only when they are inversely proportional to the arms from which they are suspended.""