Charles Darwin

"I think I have never been so sore and stiff in my life."

"The possession of wealth leads to the desire of more."

"The true man is the intellectual individual."

"To suppose that the eye could have been produced by natural selection seems, I freely confess, absurd in the highest degree."

"Multiply, vary, let the strongest live and the weakest die."

"Endless forms most beautiful and most wonderful have been, and are being, evolved."

"There is grandeur in this view of life."

"The sight of feathers in a peacock's tail makes me sick, so great is my aversion to that belief in creation."

"The fact that life has evolved is now to me the most certain of all facts."

"I have no faith in anything short of actual measurement and the Rule of Three."

"Anything which vibrates is light."

"Such are the effects of a few years of absence on the human heart and brain."

"I was much struck by certain facts in the distribution of the inhabitants of South America."

"The very essence of instinct is that it's followed independently of reason."

"Before I had found out that the simpler explanations of nature generally prove to be the true ones."

"I have attempted to write truthfully and candidly about the great interest of the subject."

"The struggle for existence will always be there in a multitude of forms."

"My mind seems to have become a kind of machine for grinding general laws out of large collections of facts."

"The more one thinks the more one finds that there is to think about."

"I believe all this suffering would not have been inflicted unless for some great purpose."

"The very essence of conquest is to leave nothing to regret either to the conqueror or the conquered."

"Sympathy will have been increased through natural selection; for those communities, which included the greatest number of sympathetic members, would flourish best, and rear the greatest number of offspring."

"Nothing can be more impossible than to conceive that this immense multitude of men should be supported."

"From the most humble and strange beginnings endless forms most beautiful and most wonderful have been."

"I am convinced a few more years of such labour as I have been accustomed to perform would make me utterly worn out."

"It is not the strongest of the species that survives; it is the most adaptable."

"It is reasonable to expect the animal kingdom will be revolutionised."

"I am fully convinced that species are not immutable; but that those belonging to what are called the same genus are lineal descendants of some other and generally extinct species."

"Every new body of discovery is, in a manner, a new creation."

"There is no exception to the rule that every organic being naturally increases at so high a rate, that if not destroyed, the earth would soon be covered by the progeny of a single pair."