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.  That we may fully comprehend the extent of this relation, we must consider, that any principal desire may be attended with subordinate ones, which are connected with it, and to which if other desires are parallel, they are by that means related to the principal one.  Thus hunger may oft be considered as the primary inclination of the soul, and the desire of approaching the meat as the secondary one; since it is absolutely necessary to the satisfying that appetite.  If an object, therefore, by any separate qualities, inclines us to approach the meat, it naturally encreases our appetite; as on the contrary, whatever inclines us to set our victuals at a distance, is contradictory to hunger, and diminishes our inclination to them.  Now it is plain that beauty has the first effect, and deformity the second:  Which is the reason why the former gives us a keener appetite for our victuals, and the latter is sufficient to disgust us at the most savoury dish. that cookery has invented.  All this is easily applicable to the appetite for generation.

From these two relations, viz, resemblance and a parallel desire, there arises such a connexion betwixt the sense of beauty, the bodily appetite, and benevolence, that they become in a manner inseparable:  And we find from experience that it is indifferent which of them advances first; since any of them is almost sure to be attended with the related affections.  One, who is inflamed with lust, feels at least a momentary kindness towards the object of it, and at the same time fancies her more beautiful than ordinary; as there are many, who begin with kindness and esteem for the wit and merit of the person, and advance from that to the other passions.  But the most common species of love is that which first arises from beauty, and afterwards diffuses itself into kindness and into the bodily appetite.  Kindness or esteem, and the appetite to generation, are too remote to unite easily together.  The one is, perhaps, the most refined passion of the soul; the other the most gross and vulgar.  The love of beauty is placed in a just medium betwixt them, and partakes of both their natures:  From whence it proceeds, that it is so singularly fitted to produce both.