Béla Bartók’s Cantata Profana (1930) retains ambiguities inherent in the Romanian myth on which it is based – a story of nine hunting-lads magically transformed into stags. This article explores the mysterious elements through psychoanalysis, positing links between darkness, Bartókian ‘night music’, and the Unconscious. Other aspects of the musical language suggest representations of Lacanian processes, specifically a regressive fantasy to the mental order of the ‘Real’. This is linked to Bartók’s experience of childhood illness, a time of perfect maternal love but profound bodily betrayal, suggesting that the stag-body represents a strong, proud transformation, ‘replacing’ the debilitated body of childhood memory. Musically, the ‘mirror-image’ scales of the opening and ending of the work are re-examined. It is proposed that they represent Bartók acknowledging loss, most importantly the loss of the myth of ‘pure sources’, which had sustained him, both musically and psychologically, up until then. This loss inevitably sought expression after a disastrous polemical debate forced him to abandon the idea of musical purity in folksong.