St. John of the Cross offers three criteria for determining whether someone has entered the dark night of the senses. The experience is something distinct from the effects of depression, melancholy, or sloth.
In brief, here are the three indications of the dark night of the senses:
The first indication makes it clear that the experience is not a matter of sloth or backsliding, of turning to other pleasures while growing lukewarm in the love of God. The second indication verifies that the experience is not simply melancholy, because there is still solicitude for God and a desire to please Him. The third indication demonstrates that the experience is not merely depression or some other “bad humor,” because the inability to meditate endures, while in the case of depression one eventually can return to former ways of thinking and behaving. All three of these indications, taken together, are a good indicator that God has led the soul into the dark night of the senses. In the following brief passage, John captures the essence of the experience of this dark night:
Since the sensory part of the soul is incapable of the goods of the spirit, it remains deprived, dry and empty. Thus, while the spirit is tasting, the flesh tastes nothing at all and becomes weak in its work….
The spirit feels the strength and energy to work, which is obtained from the substance of that interior food, even though in the beginning it may not experience the savor…. This food is the beginning of a contemplation that is dark and dry to the senses. Ordinarily this contemplation, which is secret and hidden from the very one who receives it, imparts to the soul, together with the dryness and emptiness it produces in the senses, an inclination to remain alone and in quietude. And the soul will be unable to dwell on any particular thought, nor will it have the desire to do so. If those in whom this occurs know how to remain quiet, without care or solicitude about any interior or exterior work, they will soon in that unconcern and idleness delicately experience the interior nourishment. This reflection is so delicate that usually if the soul desires or tries to experience it, it cannot do so. For, as I say, this contemplation is active while the soul is in idleness and unconcern. It is like air that escapes when one tries to grasp it in one’s hand.
Spiritual directors, please take note! This is not the time to be encouraging channel surfing in the spiritual life. This is what John is referring to in the beginning of The Ascent of Mount Carmel when he laments that some do not advance in their spiritual life: “[they] continue in their lowly method of communion with God because they do not want or know how to advance, or because they receive no direction on breaking away from the methods of beginners. Even if our Lord finally comes to their aid to the extent or making them advance without these helps, they reach the summit much later, expend more effort, and gain less merit, because they do not willingly adapt themselves to God’s work of placing them on the pure and reliable road leading to union.”
John concludes this chapter on discernment of the night of the senses by noting that God does not bring every soul into a life of contemplation:
The night of the aridity of the senses is not so continuous in [those who do not walk the road of contemplation], for sometimes they experience the aridities and at other times not, and sometimes they can meditate and at other times they cannot. God places them in this night solely to exercise and humble them, and reform their appetite lest in their spiritual life they foster a harmful attraction toward sweetness. But he does not do so in order to lead them to the life of the spirit, which is contemplation. For God does not bring to contemplation all those who purposely exercise themselves in the way of the spirit, nor even half. Why? He best knows.