For several months I have felt as if I were slipping back into clinical depression again.

The outward signs are here. The fogged thinking, lack of enthusiasm, fussiness, longing to sleep. The undertone of despair. All too generalized to ascribe to any one or cluster of causes.

Yet somehow the subtle bodily symptoms I’ve come to recognize over the decades are not really present. As a scientist in the medieval sense—someone who seeks to know—I’ve looked inwardly for years at