All relations are either qualitative or quantitative

Gentlemen, that is surely true, it is absolutely paradoxical; we cannot understand it, and we don't know what it means. But we have proved it, and therefore we know it must be the truth.

The door is wide open and all may enter, but all do not enter with equal thoughtlessness.

What is man? … What a strange union of matter and mind! A machine for converting material into spiritual force.

Ideality is preëminently the foundation of Mathematics.

Geometry, to which I have devoted my life, is honoured with the title of the Key of Sciences

The Key! it is of wonderful construction, with its infinity of combination, and its unlimited capacity to fit every lock. … it is the great master-key which unlocks every door of knowledge and without which no discovery which deserves the …