Maturana's and Varela's Tree of Knowledge is a pioneering study of cognition and epistemology showing that any sentient being's sense of reality and its environment is the product of its own self-creation ("autopoiesis"). Their account of autopoiesis has long been an important part of the vocabularies of systems theory (biological and social) and cybernetics, but, largely through the influence of the black studies theorist Sylvia Wynter, it has more recently become an important addition to various other fields in the social sciences and humanities. In my own work on Wynter and religion, Maturana and Varela have become essential conversation partners who have taught me that there is no separation between what we do and the particular way in which the world appears to us. As they put it, “every act of knowing brings forth a world. … All doing is knowing, and all knowing is doing.”