The fundamental conflict between the introspective theory of Freud and the predictive theory of Artemidorus has broad and significant implications for historians and psychohistorians. The universal claims of psychology have often led scholars to apply the findings of Freudian or other modern psychological theory to other societies, including the ancient world and Artemidorus, or to evaluate them ideologically as anticipations of Freud. In the first section these ethnocentric tendencies are briefly discussed and it is explained, why they are deeply unhelpful. Freud has been widely influential, but the actual scientific standing of his dream theory is weak and much of it is best treated as culturally relative. Then Artemidorus, like Freud himself, can be understood in his own cultural context. Artemidorus’ system of dream interpretation, which occupies the second section of this article, employs a quite unFreudian psychological model. In the final section the later importance of Artemidorus as an authority on predictive dreams and the complex transformations effected by Freud is sketched. Freud himself treated Artemidorus as a great predecessor, through his own system was profoundly different.