The most probable hypothesis, which has been advanced to explain the distinction betwixt vice and virtue, and the origin of moral rights and obligations, is, that from a primary constitution of nature certain characters and passions, by the very view and contemplation, produce a pain, and others in like manner excite a pleasure.

The uneasiness and satisfaction are not only inseparable from vice and virtue, but constitute their very nature and essence.
To approve of a character is to feel an original delight upon its appearance.

To disapprove of it is to be sensible of an uneasiness.
The pain and pleasure, therefore, being the primary causes of vice and virtue, must also be the causes of all their effects, and consequently of pride and humility, which are the unavoidable attendants of that distinction.
But supposing this hypothesis of moral philosophy should be allowed to be false, it is still evident, that pain and pleasure, if not the causes of vice and virtue, are at least inseparable from them.

A generous and noble character affords a satisfaction even in the survey; and when presented to us, though only in a poem or fable, never fails to charm and delight us.

On the other hand cruelty and treachery displease from their very nature; nor is it possible ever to reconcile us to these qualities, either in ourselves or others.