Intelligence is based on how efficient a species became at doing the things they need to survive.

I was a young man with uninformed ideas. I threw out queries, suggestions, wondering all the time over everything; and to my astonishment the ideas took like wildfire. People made a religion of them.

It at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable ones to be destroyed.

Looking to future generations, there is no cause to fear that the social instincts will grow weaker... the social instincts, - the prime principle of man's moral constitution - with the aid of active intellectual powers and the effects of habit, naturally lead to the golden rule, "As ye would that men should do to you; do ye to them likewise"; and this lies at the foundation of morality.

The normal food of man is vegetable.

How fleeting are the wishes and efforts of man! how short his time! and consequently how poor will his products be, compared with those accumulated by nature during whole geological periods. Can we wonder, then, that nature's productions should be far 'truer' in character than man's productions; that they should be infinitely better adapted to the most complex conditions of life, and should plainly bear the stamp of far higher workmanship?

The several difficulties here discussed, namely our not finding in the successive formations infinitely numerous transitional links between the many species which now exist or have existed; the sudden manner in which whole groups of species appear in our European formations; the almost entire absence, as at present known, of fossiliferous formations beneath the Silurian strata, are all undoubtedly of the gravest nature.