If the twentieth century is to be better than the nineteenth, it will be because there are among us men who walk in Priestley's footsteps....To all eternity, the sum of truth and right will have been increased by their means; to all eternity, falsehoods and injustice will be the weaker because they have lived.

Every living creature commences its existence under a form different from, and simpler than, that which it eventually attains.

No one can help another very much in these crises of life; but love and sympathy count for something.

No man is any the worse off because another acquires wealth by trade, or by the exercise of a profession; on the contrary, he cannot have acquired his wealth except by benefiting others to the extent of what they considered to be its value.

All truth, in the long run, is only common sense clarified.

The facts of variability, of the struggle for existence, of adaptation to conditions, were notorious enough; but none of us had suspected that the road to the heart of the species problem lay through them, until Darwin and Wallace dispelled the darkness.

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