reasonings on this subject can only be drawn from effects to causes; and that every argument, deducted from causes to effects, must of necessity be a… - David Hume

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.

In our reasonings concerning matter of fact, there are all imaginable degrees of assurance, from the highest certainty to the lowest species of moral evidence. A wise man, therefore, proportions his belief to the evidence.

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.