McTaggart's argument for the unreality of time is generally believed to be a self-contained argument independent of McTaggart's idealist ontology. I argue that this is mistaken. It is really a demonstration of a contradiction in the appearance of time, on the basis of certain a priori ontological axioms, in particular the thesis that all times exist in parity. When understood in this way, the argument is neither obscure or unfounded, but arguably does not address those versions of the A-theory that (...) deny that all times exist in parity. (shrink)