Every living thing is a sort of imperialist, seeking to transform as much as possible of its environment into itself.

One of the chief obstacles to intelligence is credulity, and credulity could be enormously diminished by instructions as to the prevalent forms of mendacity.

The significance of a fact is relative to [the general body of scientific] knowledge. To say that a fact is significant in science, is to say that it helps to establish or refute some general law; for science, though it starts from observation of the particular, is not concerned essentially with the particular, but with the general. A fact, in science, is not a mere fact, but an instance. In this the scientist differs from the artist, who, if he deigns to notice facts at all, is likely to notice them in all their particularity.

When the journey from means to end is not too long, the means themselves are enjoyed if the end is ardently desired.

Change is scientific; progress is ethical; change is indubitable, whereas progress is a matter of controversy.

Punctuality is a quality the need of which is bound up with social co-operation. It has nothing to do with the relation of the soul to God, or with mystic insight, or with any of the matters with which the more elevated and spiritual moralists are concerned.

What science cannot discover, mankind cannot know.