Aristotle on Substance as Primary in Time

In a notoriously obscure passage in Metaphysics 7.1 Aristotle claims that substance is primary in time. The only concrete literal interpretation suggested so far of this controversial claim is in terms of existing before and after in time. I argue that this interpretation faces serious problems. I then present a novel literal interpretation, in terms of being an appropriate subject of temporal predications, that is immune to these problems and strongly supported by philosophical and contextual considerations.