Alexander on religious melancholy

"When...people of nervous temperment are relieved from a fit of depression, their sky is uncommonly free from clouds; their hopes are lively, their spirits buoyant, and nothing can trouble them. These alternations of day and night, of sunshine and darkness, must of necessity affect the feelings in regard to all matters, temporal and spiritual; for as in a dark night every object appears black, so when the mind is overcast with gloomy clouds every view must partake of the same aspect.

To many persons this description will be unintelligible; but to others, it will be recognized at once as a just view of their own case. But when religious melancholy becomes a fixed disease, it may be reckoned among the heaviest calamities to which our suffering nature is subject. It resists all argument and rejects every topic of consolation, from whatever source it may proceed.

It feeds upon distress and despair and is displeased even with the suggestion or offer of relief. The mind thus affected seizes on those ideas and truths which are most awful and terrifying. Any doctrine which excludes all hope is congenial to the melancholy spirit; it seizes on such things with an unnatural avidity, and will not let them go.

There is no subject on which it is more vain and dangerous to theorize than our religious experience. It is therefore of unspeakable importance that ministers of the gospel, who have to deal with diseased consciences, should have had some experience themselves in these matters."

-- Archibald Alexander, Thoughts on Religious Experience (p. 35)