"You'd be surprised! I've had a few classes manage serviceable definitions. But yes: ultimately, any categorization of phenomena into 'magic' and 'not magic' is arbitrary, because the multiverse is a very big place and there is always a world you've never heard of where things work in a way you didn't expect. For the purposes of this class, here and now, the definition of magic is: a power enacted by the mind—that is, if you don't have a conscious experience, you can't do it—but not entangled with the body—that is, it is not accomplished by muscle movements or mediated by organ function, and its functions are not constrained or empowered by the state of your physical being except in the most general sense where by and large people need to be conscious in order to take actions. You may feel free to quibble with my wording, and if you come up with particularly entertaining or enlightening quibbles I might even count them toward an eventual extra credit score."