This article examines the theories of C.G. Jung and W.R. Bion. Their comparison is based on the identification of a paradigm common to the two authors, emerging especially after Bion’s formulation of O. From this common paradigm emerges the possibility of usefully comparing, both in an epistemological and clinical sense, several specific aspects of the two theories that, although they do not exhaust the similarities, seem particularly relevant. Among these aspects they are: the role of the numinous/religious, O, the collective unconscious and the Self, pre-conception, the archetype-as-such, libido, K-function and symbolism, transcendent function and transcendent position, biocularity, projective identification, as well as the fundamental role of the teleological nature that both theorisations share.