The only use of knowledge of the past is to equip us for the present.

What is morality in any given time or place? It is what the majority then and there happen to like and immorality is what they dislike.

A science which hesitates to forget its founders is lost.

In modern times the belief that the ultimate explanation of all things was to be found in Newtonian mechanics was an adumbration of the truth that all science, as it grows towards perfection, becomes mathematical in its ideas.

Imagination is not to be divorced from the facts. It is a way of illuminating the facts.

Aristotle discovered all the half-truths which were necessary to the creation of science.

Knowledge shrinks as wisdom grows.