T 2.2.11.3

But there is another principle that contributes to the same effect. I have observ'd 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 consider'd as the primary inclination of the soul, and the desire of ap|proaching the meat as the secondary one; since 'tis 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 'tis 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.