These incredible posters illustrate two stories with a single image

At first glance, this looks like a poster for Harry Potter, but is there something more going on? These posters illustrate famous stories with minimalist images, but hide a second story inside.

Using a technique that evokes the Rubin vase illusion, Colombian advertising agency Lowe/SSP3 created these images for the Colsubsidio Book Exchange. Come with Harry Potter, leave with The Iliad.

Colsubsidio Book Exchange [Ads of the World via Neatorama]