Don't know what the link is and I imagine it's good, but 'corruption' artistically was meant more in the way of scenarios being 'staged', like still life arrangements, and the Pre-Raphaelites preferred natural subjects and indeed the natural world as backdrops. Apparently this happened after Raphael; I can never quite make my mind up whether Raphael therefore was supposed to be the pinnacle of perfection or the start of 'corruption'; I think the former. Either way, I say 'corruption' inverted commas because it wasn't corruption in the way we now normally think of. Hope this helps; oh, I've noticed the link to wikepedia and I like their explanations!