Re: Hmmm...why didn't I think of that...
The Philosopher's Stone is a well-known mythical supernatural item, like the Holy Grail, and is pretty much public domain. I was somewhat irritated that someone thought it had to be changed to "Sorcerer's Stone" for the dimbulb Americans. I generally order two Harry Potter books when they come out: the British edition, for the original text and covers, and the American edition, for the superb Mary Grandpre illustrations.