In The Interpretation of Dreams, Freud refers several times to Artemidorus's dream book Oneirocritica dating back to the second century CE as a precursor of his own book. This article explores the meaning of this reference by analysing the interrelations between philological scholarship and emerging psychoanalysis in late nineteenth-century Vienna. Freud's own reading of Artemidorus's text developed in a critical dialogue with the work of the Austrian philologist Theodor Gomperz and his student Friedrich S. Krauss, who produced the first modern German translation of the Oneirocritica. The symbolic method of the ancient dream books, adapted by Freud in later editions of The Interpretation of Dreams for sexual symbolism, did however also inspire dissenting interpretations within the early psychoanalytic movement. Freud's turn to sexual folklore and ethnography, embodied by Krauss's later studies, played a strategic role in these conflicts over dream interpretation.