(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.