The sense of justice and injustice is not deriv'd from nature, but arises artificially... from education, and human conventions.

Actions may be laudable or blameable; but they cannot be reasonable: Laudable or blameable, therefore, are not the same with reasonable or unreasonable. The merit and demerit of actions frequently contradict, and sometimes controul our natural propensities. But reason has no such influence. Moral distinctions, therefore, are not the offspring of reason. Reason is wholly inactive, and can never be the source of so active a principle as conscience, or a sense of morals.

Morals excite passions, and produce or prevent actions. Reason of itself is utterly impotent in this particular. The rules of morality, therefore, are not conclusions of our reason.

Morality is a subject that interests us above all others: We fancy the peace of society to be at stake in every decision concerning it; and 'tis evident, that this concern must make our speculations appear more real and solid, than where the subject is, in a great measure, indifferent to us. What affects us, we conclude can never be a chimera; and as our passion is engag'd on the one side or the other, we naturally think that the question lies within human comprehension; which, in other cases of this nature, we are apt to entertain some doubt of. Without this advantage I never should have ventur'd upon a third volume of such abstruse philosophy, in an age, wherein the greatest part of men seem agreed to convert reading into an amusement, and to reject every thing that requires any considerable degree of attention to be comprehended.

There is an inconvenience which attends all abstruse reasoning. That it may silence, without convincing an antagonist, and requires the same intense study to make us sensible of its force, that was at first requisite for its invention. When we leave our closet, and engage in the common affairs of life, its conclusions seem to vanish, like the phantoms of the night on the appearance of the morning; and 'tis difficult for us to retain even that conviction, which we had attain'd with difficulty.

We speak not strictly and philosophically when we talk of the combat of passion and of reason. Reason is, and ought only to be the slave of the passions, and can never pretend to any other office than to serve and obey them.

There is no method of reasoning more common, and yet none more blameable, than in philosophical debates to endeavour to refute any hypothesis by a pretext of its dangerous consequences to religion and morality. When any opinion leads us into absurdities, 'tis certainly false; but 'tis not certain an opinion is false, because 'tis of dangerous consequence.

Tis evident, that sympathy, or the communication of passions, takes place among animals, no less than among men. Fear, anger, courage and other affections are frequently communicated from one animal to another [...] And 'tis remarkable, that tho' almost all animals use in play the same member, and nearly the same action as in fighting; a lion, a tyger, a cat their paws; an ox his homs; a dog his teeth; a horse his heels: Yet they most carefully avoid harming their companion, even tho' they have nothing to fear from his resentment; which is an evident proof of the sense brutes have of each other's pain and pleasure.

Love in animals, has not for its only object animals of the same species, but extends itself farther, and comprehends almost every sensible and thinking being. A dog naturally loves a man above his own species, and very commonly meets with a return of affection.

The very port and gait of a swan, or turkey, or peacock show the high idea he has entertain'd of himself; and his contempt of all others. This is the more remarkable, that in the two last species of animals, the pride always attends the beauty, and is discover'd in the male only. The vanity and emulation of nightingales in singing have been commonly remark'd [...] All these are evident proofs, that pride and humility are not merely human passions, but extend themselves over the whole animal creation.