Process and Reality: An Essay in Cosmology (cite: Whitehead, 1929) (1929) is Alfred North Whitehead’s magnum opus, presenting a comprehensive metaphysical system — the “philosophy of organism” — in which actual occasions (momentary events of experience) are the fundamental constituents of reality, constituting themselves through prehension and concrescence.
The book develops a systematic alternative to substance metaphysics, arguing that relations are ontologically prior to relata, that experience is the basic character of reality (not limited to conscious organisms), and that the universe is a creative advance into novelty. Whitehead’s “categoreal scheme” — his formal statement of the ultimate categories of reality — constitutes one of the most ambitious attempts in Western philosophy to build a metaphysics in which process, relation, and creativity replace substance, property, and persistence.
The text is notoriously difficult, and its reception has been uneven: celebrated in process theology and the process philosophy tradition, largely marginalized in analytic philosophy, and increasingly rediscovered by scholars working on relational ontology, the ontological turn, and the intersection of Western and Indigenous metaphysics.