It is not the strongest of the species that survives, nor the most intelligent that survives. It is the one that is the most adaptable to change, that lives within the means available and works co-operatively against common threats.

When it was first said that the sun stood still and world turned round, the common sense of mankind declared the doctrine false; but the old saying of Vox populi, vox Dei [the voice of the people is the voice of God], as every philosopher knows, cannot be trusted in science.

On seeing the marsupials in Australia for the first time and comparing them to placental mammals: “An unbeliever . . . might exclaim 'Surely two distinct Creators must have been at work'”

I feel like an old warhorse at the sound of a trumpet when I read about the capturing of rare beetles.

If a person asked my advice, before undertaking a long voyage, my answer would depend upon his possessing a decided taste for some branch of knowledge, which could by this means be advanced. No doubt it is a high satisfaction to behold various countries and the many races of mankind, but the pleasures gained at the time do not counterbalance the evils.

... not one living species will transmit its unaltered likeness to a distant futurity.

Nothing before had ever made me thoroughly realise, though I had read various scientific books, that science consists in grouping facts so that general laws or conclusions may be drawn from them.