The Harvard philosopher Donald C. Williams (1899-1983) was a key figure in twentieth-century philosophy, but underappreciated. He played a crucial role in reviving metaphysics at a time when other philosophers would ridicule, criticise, and commit it to the flames. He constructed an explanatorily powerful and parsimonious ontology and cosmology founded on logic, science, and common sense. His most influential articles were on the metaphysics of properties ('The Elements of Being') and the metaphysics of time ('The Sea Fight Tomorrow', 'The Myth of Passage'). His ontology of abstract particulars or tropes and his four-dimensional manifold theory of time remain leading hypotheses in metaphysics. Because of his novel contributions and his defence of metaphysics he made a lasting impact on philosophers of the next generation who in turn believed in the substance of metaphysical inquiry. A. R. J. Fisher brings together Williams's seminal articles in metaphysics along with previously unpublished essays which shed new light on his philosophical outlook and complete his metaphysical vision. This volume, with its comprehensive Introduction, will be the definitive source for Williams's work, both for historians of analytic philosophy and for contemporary metaphysicians.