Charles Darwin

"I have deeply regretted that I did not proceed far enough at least to understand something of the great leading principles of mathematics."

"Owing to this struggle for life, any variation, however slight, if it be in any degree profitable to an individual of any species, will tend to the preservation of that individual."

"The war of nature is not incessant, not one of universal slaughter, unless so at rare intervals."

"If I had my life to live over again, I would have made it a rule to read some poetry every single day of my life."

"We must, however, acknowledge, as it seems to me, that man with all his noble qualities still bears in his bodily frame the indelible stamp of his lowly origin."

"I feel most deeply that this whole question of Creation is too profound for the human intellect."

"On my return home, my father advised me to think deliberately over what profession to follow."

"The sight of a feather brings me joy beyond measure."

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

"I have tried to pay attention to every fact which could tell against me."

"The variations which no naturalist has yet defined appear to me to accumulate without limit."

"After having been at sea for some weeks, a return to land is a blessing I cannot adequately describe."

"It is not the want of affection, but a want of power to express it, which often causes disappointment."

"The day may come when all that we hold dear will vanish like morning mist."

"I wish I had appreciated my mother more before she passed."

"A person cannot investigate nature without first loving it."

"The discovery of a new species never ceases to fill me with wonder."

"There is a world of difference between understanding nature and commanding it."

"I cannot help wondering at the power and extent of natural selection."

"The more we know, the more we realize how much more there is to know."

"It is impossible to conceal our beliefs for long."

"My respect grows for the native peoples with every observation I make."

"The development of moral feelings is of the highest importance for a happy civilization."

"I am a firm believer in the power of habit to shape our character."

"It is curious how the mind clings to old habits, even when proven wrong."

"The patience required for scientific work is immense beyond measure."

"Without the aid of others, no great work can ever be accomplished."

"The fear of the unknown drives men to seek knowledge."

"It would be impossible to imagine any diversity of form and structure without the principle of adaptation."

"I have found that observation requires not just eyes, but an open mind."