Saint John of the Cross next describes the various forms of spiritual anger that manifest themselves in those who have not been purified by the dark night.
Because of the strong desire of many beginners for spiritual gratification, they usually have many imperfections of anger. When the delight and satisfaction procured in their spiritual exercises passes, these beginners are naturally left without any spiritual savor. And because of this distastefulness, they become peevish in the works they do and easily angered by the least thing, and occasionally they are so unbearable that nobody can put up with them. This frequently occurs after they have experienced in prayer some recollection pleasant to the senses.
After the delight and satisfaction are gone, the sensory part of the soul is naturally left vapid and zestless, just as a child is when withdrawn from the sweet breast. These souls are not at fault if they do not allow this dejection to influence them, for it is an imperfection that must be purged through the dryness and distress of the dark night.
Among these spiritual persons there are also those who fall into another kind of spiritual anger. Through a certain indiscreet zeal they become angry over the sins of others, reprove these others, and sometimes even feel the impulse to do so angrily, which in fact they occasionally do, setting themselves up as lords of virtue. All such conduct is contrary to spiritual meekness.
Others, in becoming aware of their own imperfections, grow angry with themselves in an unhumble patience…. Some, however, are so patient about their desire for advancement that God would prefer to see them a little less so.
I have heard several priests talk about the connection between lack of moderation in eating and anger, but the connection became quite clear after reading this passage from Saint John. Just as some of us walk around with a spiritual sweettooth, and get cranky when we are denied our spiritual Disneylands, sometimes when we are denied food (or choose to fast), there is a tendency to get a bit edgy and irascible. At least this has been my experience.
All of this points, I think, to the value of fasting as a practice to help us grow spiritually. If we can learn how to do without (and to do so without grumbling or lashing out), we will come a little closer to imaging the Suffering Servant of Isaiah.