This paper will focus on complexity systems theory as a sensibility that informs my psychoanalytic psychotherapeutic practice. Complexity systems theory, along with its non-linear siblings of fractal geometry and chaos theory, will be seen to constitute a conceptual triad that explains the ontological fact of infinite interpenetration of all phenomena and entities in the universe. This fact will be seen to inform a cosmic contextualism that underwrites a set of clinical guidelines for working within a complexity sensibility. A clinical vignette will illustrate a momentous tipping point whereby resisting a trauma informed retreat into formulaic interventions and staying in complexity created the relational condition that allowed a surprising twinship to emerge. A detailed inquiry disclosed the nature of the therapist’s trauma to be the intergenerational transmission of traumatizing systemic antisemitism within Canadian medical schools of the 1930s and 1940s.