A short proto-theory of clinical medicine is proposed. The practice of medicine basically depends on three general concepts: an individual patient image, the individual disease course of this patient, and an expectation of the future development of the disease. Physicians use heuristics for the cognitive processing of these concepts. Basic clinical heuristics are put into three algorithms: a history-based-learning algorithm, a diagnostic-inferencing algorithm, and a prognostic-planning algorithm. The text provides a short compendium for cognitive engineers as well as for medical practitioners.