Science is organized common sense where many a beautiful theory was killed by an ugly fact.

Agnosticism is not properly described as a "negative" creed, nor indeed as a creed of any kind, except in so far as it expresses absolute faith in the validity of a principle which is as much ethical as intellectual.

Surely there is a time to submit to guidance and a time to take one's own way at all hazards.

Irrationally held truths may be more harmful than reasoned errors.

Genius, as an explosive power, beats gunpowder hollow.

The foundation of all morality is to have done, once and for all, with lying; to give up pretending to believe that for which there is no evidence, and repeating unintelligible propositions about things beyond the possibilities of knowledge.

Our reverence for the nobility of manhood will not be lessened by the knowledge that man is in substance and in structure, one with the brutes; for he alone possesses the marvellous endowment of intelligible and rational speech whereby he has slowly accumulated and organized the experience which is almost wholly lost with the cessation of individual life in other animals; so that he now stands raised above it as on a mountain-top, far above the level of his humble fellows, and transfigured from his grosser nature by reflecting, here and there, a ray from the infinite source of truth.