It is a popular delusion that the scientific enquirer is under an obligation not to go beyond generalisation of observed facts...but anyone who is practically acquainted with scientific work is aware that those who refuse to go beyond the facts, rarely get as far.

The chess-board is the world, the pieces are the phenomena of the universe, the rules of the game are what we call the laws of Nature. The player on the other side is hidden from us.

A man's worst difficulties begin when he is able to do as he likes.

I really see no harm which can come of giving our children a little knowledge of physiology. ... The instruction must be real, based upon observation, eked out by good explanatory diagrams and models, and conveyed by a teacher whose own knowledge has been acquired by a study of the facts; and not the mere catechismal parrot-work which too often usurps the place of elementary teaching.

I protest that if some great Power would agree to make me always think what is true and do what is right, on condition of being turned into a sort of clock and would up every morning before I got out of bed, I should instantly close with the offer.

The improver of natural knowledge absolutely refuses to acknowledge authority, as such. For him, skepticism is the highest of duties; blind faith the one unpardonable sin.

We are prone to see what lies behind our eyes, rather than what apprears before them.