Smithsonian Magazine has an insightful article on magic written by Teller of Penn and Teller:
But magic's not easy to pick apart with machines, because it's not really about the mechanics of your senses. Magic's about understanding””and then manipulating””how viewers digest the sensory information.
Later on, he refers to magic as an art. Given his description here, I think he has a point. Today, we typically think in terms of inputs and outputs: if I insert $x materials, I should get $y widgets. A magic act, though, isn't about raw materials, but what you make of them. The trick may be illusion, but it isn't merely illusion. We are delighted to be misguided when watching a magic trick. It achieves something more than the sum of its parts. In a similar way, more traditional forms of art — painting, writing and the like — may often seem superfluous, but there is a lot going on beyond what we immediately register.