By the sixteenth century, the era of Saint John of the Cross, the Church recognized three particular enemies of the soul: the World, the Flesh, and the Devil. While this formulation doesn’t appear explicitly until the high Middle Ages, the monastic Fathers wrote about spiritual warfare from a similar set of considerations. Their view of the soul was based on the three appetites or desires that move us to act. The lowest, the concupiscible, is our desire for bodily life and pleasure. The corruption of this desire is what Saint John calls the Flesh. He also says that the attacks against by the Flesh are the most tenacious and continue as long as the old Man survives in us. This comports well with what the monks of old warned their disciples, that sexual desire and the desire for inordinate eating will be temptations to the end of our lives for most of us.
The virtues that help us to govern these desires are especially temperance and courage.
More noble than the concupiscible desires are the irascible desires, which we normally think of as related to emotions like anger and sadness. We desire safety, honor, recognition, and the freedom to act, and when these are thwarted we are tempted to lash out in anger or grow sullen and cynical. These desires are nobler because they relate our souls to the world around us, rather than simply to our own bodies. The corruption of these desires is what John calls the World. He says that these are the simplest temptations to vanquish.
The virtues that we need to cultivate to fight back against the World are courage and especially justice.
The most difficult temptations to understand arise from the Devil, and these attack the intellect and will. The will is our “intellectual appetite,” meaning it is what we want to do after we’ve weighed options and made a decision. The vice that is especially dangerous here is pride, which is the vice that characterizes the Devil himself. The cardinal virtue that needs cultivating in this case is prudence. The Church’s own reflection on the Incarnation helps us to see the importance of the dispositions of humility and obedience. These two stances, modeled for us by Christ Himself, show us how to develop a truly Christian prudence, one that can fight back against the Devil’s temptations.
What are these temptations? The Devil wants us to misjudge, to choose what is evil disguised as good. In other words, we are likely to be led astray by projects that appear to be good, but in fact weaken our docility to God and to the obligations attached to our state of life. This is connected to pride because we often choose tasks with an unrealistic view of our own ability to bring them to a good completion. We may seek out projects that will make us appear more virtuous to others than we are, rather than choosing a less spectacular path that leads to genuine virtue.
John of the Cross offers us three precautions when engaging in spiritual warfare against the Devil. He is writing for contemplative religious, and so we will need to translate these into terms that will make sense in the world. But it probably is good to bear in mind his original teaching in its religious context, so that we don’t subtly weaken his points.
(Here is the Introduction to the whole series. Here are The First Precaution Against the World and The Second and Third Precautions Against the World. Here are Part 1 of the Introduction to Precautions Against the Flesh and Part 2 of the Introduction to Precautions Against the Flesh. Here are The First, Second and Third Precautions Against the Flesh.)

