I hope you won´t mind me giving a quite general statement, but everything we see might as well be an illusion. Theoretical physicists are seriously studying the possibility that our tri-dimensional world is actually a hologram, a projection of a 2D surface. In that case, photography would be an illusion reproducing another illusion. But being a frozen moment in time (or better space-time), photography has a strong power of communicating a concept or an idea.