But when on shore, & wandering in the sublime forests, surrounded by views more gorgeous than even Claude ever imagined, I enjoy a delight which none but those who have experienced it can understand.

Even people who aren’t geniuses can outthink the rest of mankind if they develop certain thinking habits.

We are optimists, until we are not.

I have been speculating last night what makes a man a discoverer of undiscovered things. As far as I can conjecture the art consists in habitually searching for the causes and meaning of everything which occurs.

Formerly Milton's Paradise Lost had been my chief favourite, and in my excursions during the voyage of the Beagle, when I could take only a single small volume, I always chose Milton.

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.

A grain in the balance will determine which individual shall live and which shall die - which variety or species shall increase in number, and which shall decrease, or finally become extinct.