For most of his adult life Charles Darwin, F.R.S. (1809-1882) suffered from a chronic indisposition, the nature of which has remained a mystery. Until Colp's exhaustive account of the illness, the principal symptoms cited were palpitation, dyspepsia, headache, weakness and exhaustion. Such symptoms suggested to many a psychosomatic disorder, although this has not gone uncriticized. The only physical diagnosis to have received attention was Chagas' disease, an infection to which Darwin might have been exposed to in Argentina. However, since Woodruff's effective intervention, that diagnosis finds little support; and today the psychogenic hypothesis holds the field. But how reliable is this presumption in the light of the much fuller medical information available in Colp's review, much of it derived from unpublished letters, which subsequently have been or are being published?10 The important impression gained from Colp's account is the severity of the repeated attacks Darwin endured for over 35 years. He knew he was truly ill, as did his family, friends and at least some of his doctors. The desperation of his efforts on many occasions to pursue his scientific work despite prostration makes nonsense of the suggestion, for example, that he induced vomiting attacks merely to avoid going to dinner parties.