In this essay, I examine the possibility of creating an ontological framework for transhuman philosophies based on the metaphysics of Baruch Spinoza. I pay special attention to his account of mereology, change, and resilience. In describing this ontological framework, I argue that a Spinozist account of human nature is beneficial to transhumanism insofar as it provides two crucial components: first, an open ontology capable of capturing change and individualizing the essence of human beings; second, a criterion for the limitation of mutation that operates as a safeguard against the disaggregation of the human whole.