Next to its physiological function, every organ of our body has still another function, a psychological one. Having mentioned the psychological significance of the circulatory apparatus in general, and the psycho-physiological and psycho-pathological significance of the heart, the author summarizes the results of investigations into the relationship between psychical processes and the vascular system of the heart with normal people and with patients both waking and in hypnosis. The structure of a man's personality and his temperamental qualities play a part in his susceptibility to the contents of psychical experiences and in his psycho-physiological way of reacting.