Among the scenes which are deeply impressed on my mind, none exceed in sublimity the primeval [tropical] forests, ... temples filled with the varied productions of the God of Nature. No one can stand in these solitudes unmoved, and not feel that there is more in man than the mere breath of his body.

As man advances in civilization, and small tribes are united into larger communities, the simplest reason would tell each individual that he ought to extend his social instincts and sympathies to all members of the same nation, though personally unknown to him. This point being once reached, there is only an artificial barrier to prevent his sympathies extending to the men of all nations and races.

I agree with Agassiz that dogs possess something very like conscience.

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

If man had not been his own classifier, he would never have thought of founding a separate order for his own reception.

It is a fatal fault to reason whilst observing, though so necessary beforehand and so useful afterwards.

The willing horse is always overworked.