Descriptions of the musical temperament are, as a rule, vivacious and luminous, thrillingly interesting. If a competent analyst would follow Stokowski for one day during the season and picture in high lights, full of concrete examples, the experience and behavior of this great conductor from the whirl of emotional enthusiasms and conflicts into which he awakens in the morning to the convivial abandon during refreshments after the evening performance, we should have a spicy and animated picture of the musical temperament. If written by the smart commentator in the columns of _Esquire_, it might even be racy. Such pictures have often been drawn in fragments. A similar picture might be made exclusively by direct quotation from biographies, autobiographies, and letters of great musicians, such as Beethoven and Wagner, whose lives are now on record. The temperamental musician is not competent to analyze himself because he does not see himself as others see him. Literary chats about musicians are full of quirks and eccentricities giving realistic examples of a temperamental life. These might be organized into a fairly complete characterization of a distinctive musical temperament. All such exhibits would be of the emotional type, dramatic extravaganzas, interesting and significant, and there are many such extant. The inceptive science of the psychology of music takes a different point of view, aiming to account for the highly temperamental person partly in terms of heredity and partly in terms of inherent elements in the situation in which he lives and performs. The music psychologist must content himself to deal in a cold analytical way with verifiable and orderly facts in order to contribute something toward a scientific foundation for a systematic and functional psychology of the musical mind. In attempting this approach, I realize how tame and stilted such an effort must seem to the fiery musical temperament; and even at its best the psychologist will regard the account as speculative, because it is seldom based upon experiment. I have delved into musical biography and autobiography of great musicians with an eye toward the discovery of their outstanding mental characteristics from a psychological point of view. On this basis I must make a bold venture by attempting to trace the elements in a musical situation which lead to the development of temperamental behavior and thus contribute toward the answer to the question, "What makes a musician temperamental?"