In the Hobbit: An Unexpected Journey, Gandalf attempts to convince Saruman that the "Necromancer" i.e. Sauron, has returned, but Saruman dismisses Gandalf saying:
Saruman: That's absurd. No such power exists in this world. This "Necromancer" is nothing more than a mortal man, a conjurer dabbling in black magic.
Would this mean that humans could learn and use magic? Or would Saruman be talking about what we would consider a magician in our world?