Some experience of popular lecturing had convinced me that the necessity of making things plain to uninstructed people, was one of the very best means of clearing up the obscure corners in one's own mind.

Men can intoxicate themselves with ideas as effectually as with alcohol or with bang and produce, be dint of serious thinking, mental conditions hardly distinguishable from monomania.

My belief is that no human being or society composed of human beings ever did or ever will come to much unless their conduct was governed and guided by the love of some ethical ideal.

The question of all questions for humanity, the problem which lies behind all others and is more interesting than any of them, is that of the determination of man's place in nature and his relation to the cosmos.

To a person uninstructed in natural history, his country or sea-side stroll is a walk through a gallery filled with wonderful works of art, nine-tenths of which have their faces turned to the wall. Teach him something of natural history, and you place in his hands a catalogue of those which are worth turning around. Surely our innocent pleasures are not so abundant in this life, that we can afford to despise this or any other source of them.

Science is simply common sense at its best.

The only people, scientific or other, who never make mistakes are those who do nothing.