Nothing exists for itself alone, but only in relation to other forms of life

I am a firm believer, that without speculation there is no good and original observation.

Sympathy for the lowest animals is one of the noblest virtues with which man is endowed.

I am not very sceptical, — a frame of mind which I believe to be injurious to the progress of science. A good deal of scepticism in a scientific man is advisable to avoid much loss of time, but I have met with not a few men, who, I feel sure, have often thus been deterred from experiment or observations, which would have proved directly or indirectly serviceable .

Owing to this struggle for life, any variation, however slight and from whatever cause proceeding, if it be in any degree profitable to an individual of any species, in its infinitely complex relationship to other organic beings and to external nature, will tend to the preservation of that individual, and will generally be inherited by its offspring.

...he who remains passive when over-whelmed with grief loses his best chance of recovering his elasticity of mind.

When the views entertained in this volume on the origin of species, or when analogous views are generally admitted, we can dimly forsee that there will be a considerable revolution in natural history.