Because wasting perfectly good* food is unwitchy. You wanna divine using a can of ravioli? Empty it into a pan, cook it, and observe how it cooks as the sauce boils over. Meditate on the movement of each raviolo. Then - and this is the important part - let it cool a little, season it, and eat it.
(edit: I mean good as in edible, not good as in high quality)