Natural Human Inclinations. (Rewritten).

There is another group of principles that, for several reasons, can be placed under the broad heading of Desires, though they are clearly different in some ways from that form of desire known as the appetites.These principles, which are called the Propensities or Propensive principles in order to distinguish them from the appetites, seem to depend less on the condition of the physical body for their existence and activity than the appetites do. These are what we commonly call inclinations. Since they are, to some extent, removed from the outward senses, which form the basis for the action of the appetites, they plainly stand closer to the higher and more important principles of our nature. For that reason, in the usual way we judge the different parts of our mental constitution, they are seen as holding a higher rank. Some of the principles that belong under this general heading — for it is not necessary to list them all, and even less necessary to examine them one by one — are the principle of self-preservation, or the desire for continued existence; curiosity, or the desire for knowledge; sociality, or the desire for society; self-love, or the desire for happiness; the desire for esteem; and several others.

Human Appetites. (rewritten)

It is worth keeping in mind that the main human appetites and propensities, in their particular forms, are really different expressions of desire. So if it matters that our desires be rightly governed, then it matters just as much that the specific appetites and propensities desire takes on, in the proper circumstances, be rightly governed too. The same is true of the affections. Like the appetites and propensive principles, the affections have desire as one of their essential and leading elements, and they also can run into excess.

(1) — The appetites are good when they remain in their proper place. But when they are not rightly regulated — when they are not kept to their proper occasions and objects — they become a source of serious harm. I believe it is generally understood that excessive indulgence of the appetites, the “lower passions,” as they are sometimes called, is the real source of inward moral impurity. This is a state of mind that, sadly, most people probably know from experience better than any explanation could describe. The way people speak about the appetites shows clearly what they think about this. Whenever the appetites move beyond their proper sphere and measure, people describe them as low, degrading, and polluting, and compare those who indulge them in that way to swine wallowing in the mud.

Our own consciousness also bears witness to this. When the appetites are fully subdued and kept in their place, the person who experiences them — at least as far as the appetites are concerned — feels pure in heart. But when this is not the case, there is not only guilt, but degradation. There is an inward awareness of what may be called, figuratively, a stain or blot on the mind. The soul knows, by its own experience, that it is not what it is at other times. 

A holy soul may be compared to a mirror into which God may look and see the features of his own character reflected. But when the soul yields to the improper influence of the appetites, that mirror becomes stained and darkened, and God is no longer seen in it.