Four hundred years of human history, give or take. Should've known that'd spark your interest, I'll go get it.

[It lives on the bookshelf in his bedroom, so it's only a quick trip up the flight of stairs that lead up to the mezzanine level, before he's returning with the leather bound book.

It's lightly burned, the same state it was in when Crowley rescued it from the burning bookshop, which explains the wariness in his expression as he hands it over.]

Be careful with it, that's the only thing I've got from home.

[From Aziraphale is what he means, but he's not saying that out loud.]