Jakob Klaesi was born on the 29th May 1883 in Glarus Canton (Switzerland) and was assistant and later head physician at the Psychiatric University Hospital in Zurich, directed by Eugen Bleuler. Klaesi directed the new Psychiatric Outpatient Department in Basel from 1923 to 1926 and later founded the Schloss Kronau private clinic in the Zurich Canton. In 1933 he became director of the Psychiatric University Hospital in Bern. His attitude toward somatic treatment methods was skeptical, although about 1920 he founded a psychiatric sleep cure with Somnifen. Klaesi was primarily a psychotherapist and interested in the psychodynamics of his patients. With his great empathy, he was able to understand especially well their expressive behaviour. This capacity for empathy and his philosophic orientation enabled him to develop a phenomenological analysis of expression. He died on the 17th August 1980. Differences and parallels to the thinking of Alfred Adler and Karl Jaspers are discussed.