The question posed by the title of this paper has been debated in the psychiatric literature both here and abroad for many years, as evidenced by such distinctions as endogenous vs. psychogenic or reactive, and psychotic vs. neurotic, forms of depression. This author concludes that depressive illness can be seen as disease in the sense that its manifestations are deviations from normal biological functions, and as reaction in the sense that it is a response to a crisis situation, resulting in a catastrophic lowering of self-esteem. But the therapeutic skill of the psychiatrist is best displayed when he understands the patient's depression as posture, the symptoms of which are forms of communication.Abstract Teaser