The pleasing sensation arising from beauty; the bodily appetite for generation; and a generous kindness or good-will.

The origin of kindness from beauty may be explained from the foregoing reasoning.

The question is how the bodily appetite is excited by it.
The appetite of generation, when confined to a certain degree, is evidently of the pleasant kind, and has a strong connexion with, all the agreeable emotions.

Joy, mirth, vanity, and kindness are all incentives to this desire; as well as music, dancing, wine, and good cheer.

On the other hand, sorrow, melancholy, poverty, humility are destructive of it.
From this quality it is easily conceived why it should be connected with the sense of beauty.
But there is another principle that contributes to the same effect.
I have observed that the parallel direction of the desires is a real relation, and no less than a resemblance in their sensation, produces a connexion among them.