A research neuroscientist in his fifties, who has recovered from endogenous depression after several years, describes the experience and makes some comments on treatment and management. He found electroconvulsive therapy, mianserin, lithium carbonate and diazepam acceptable. He considers that occupational therapy and conventional psychotherapy were counter-therapeutic. He stresses how physically ill he felt when depressed, and compares this with prolonged influenza. He hypothesises that the underlying psychological disorder in endogenous depression is the learned extinction of optimistic thoughts, and suggests that any psychotherapy used should be aimed at restoring these.