Psychedelic-assisted psychotherapy has re-emerged as treatment for a variety of afflictions, such as depression, anxiety, PTSD, OCD, fear, addiction, etc. Recent evidence suggests that a core efficacious component in such therapy is the inducement of ‘mystical experiences’ – experiences that we can seemingly recognise from certain taxonomies of ‘mysticism’. But such experiences can be more widely subsumed under the category of ‘metaphysical experiences’ and, in so doing, can be further explored through the variety of metaphysical positions that philosophy offers, such as neutral monism, idealism, the transcendent, dualism, and types of physicalism. It will be proposed that exploring psychedelic-induced metaphysical experiences with recourse to metaphysics would be an important optional part of the integrative phase of psychedelic therapy, with the further conjecture that such amplified cognizance of these experiences will lead to longer-term benefits to the participant. Though this proposal of Metaphysics Integration in Psychedelic Therapy maintains a neutral metaphysical position, in this particular session Peter will explore the mystical experiences referred to by the term ‘oceanic feeling’, with its origins (via Freud and Rolland) in the metaphysics of Spinoza, a neutral monism.