Harry: You can’t DO that!
Minerva McGonagall: It’s only a transfiguration; an animagus transformation, to be exact—
Harry: You turned into a cat! A SMALL cat! You violated Conservation of Energy! That’s not just an arbitrary rule – rejecting it destroys unitarity and then you get FTL signaling! And cats are COMPLICATED! A human mind can’t just visualize a whole cat’s anatomy and, and all the cat biochemistry, and what about the neurology? How can you go on thinking using a cat-sized brain?
Harry: Magic isn’t enough to do that! You’d have to be a god!
—Harry’s first encounter with magic