Cassandra Clare said this quote

Pulvis et umbra sumus. It's a line from Horace. 'We are dust and shadows'. Appropriate, don't you think? Will said. It's not a long life, killing demons; one tends to die young, and then they burn your body - dust to dust, in the literal sense. And then we vanish into the shadows of history, nary a mark on the page of a mundane book to remind the world that once we existed at all.