The partnership between Wundt and Cattell proved highly productive, as the two helped to establish the formal study of intelligence. Under Wundt, Cattell became the first American to publish a dissertation in the field of psychology. The title of his German dissertation was "Psychometrische Untersuchungen" ("Psychometric Investigation"). The dissertation was accepted by the University of Leipzig in 1886. More controversially, Cattell tried to explore the interiors of his own mind through the consumption of the then-legal drug hashish. Under the influence of this drug, Cattell once compared the whistling of a schoolboy to a symphony orchestra. While recreational drug use was not uncommon among early psychologists, including Freud, Cattell's experimentation with hashish reflected a willingness to go against conventional opinion and morality.