"Let me have men about me that are fat; Yon Cassius has a lean and hungry look; Such men are dangerous." Since Shakespeare wrote these words, many writers and laymen have used similar expressions in reference to the relationship between the constitution and the psyche. Biologists, eugenists, psychologists, psychiatrists, anthropologists and physicians have likewise thought about and investigated this subject for many years. Is there any scientific evidence that the observations of people in their daily lives are correct? Are the fat good natured and the lean ill natured?
In order that the reader may best understand the contents of this monograph he must first understand the meaning of the terms constitution, character and temperament and their functional relation with one another.
To quote Kretschmer, one of the best modern authorities on this subject, "constitution is the totality of all individual characteristics which are referable to heredity." He believes that