The formation of different languages and of distinct species and the proofs that both have been developed through a gradual process, are curiously parallel.

I have long discovered that geologists never read each other's works, and that the only object in writing a book is a proof of earnestness.

The main conclusion here arrived at ... is that man is descended from some less highly organized form.

The love for all living creatures is the most noble attribute of man.

Only picture to yourself a nice soft wife on a sofa with good fire, & books & music.

...I believe there exists, & I feel within me, an instinct for the truth, or knowledge or discovery, of something of the same nature as the instinct of virtue, & that our having such an instinct is reason enough for scientific researches without any practical results ever ensuing from them.

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.