The Magician is the Magus of Power and is ruled by Mercury. He represents one's ability to create the impossible, and he is the guide to your ability to find direction and purpose, together with the tools to pull it all together.
Mercury is the Messenger of the Gods, and as such, his information is potent, special and needs your serious attention. When the Magician appears in a reading, it is time to understand that you really do have what it takes to make things happen in your life. You know when the pressure is on and you have to do something seemingly impossible - to put it into 'magician' terms, to pull a rabbit out of a hat - you have the power to do this now. But Magic is not an illusion to entertain the masses, and if anyone would try to convince you of this, run, do not walk, to the nearest exit. Magic is available to everyone who knows how to ask - it is not the province of the lucky and the talented. It is a function of belief in self, and focus, and a willingness to drop preconceived notions of what is real and what is possible. There are signs that appear in our life's journey along the road, and The Magician appears on this road and points to the way - but he also provides the tools and the impetus to create the path and the motivation to pursue it - best that you are paying attention. The interesting thing about the real world and reality is that we can only absorb and pay attention to a very tiny subset of what is going on in any given moment in any given space. Once you open your mind to the possibility of a different perspective, a different range of possibilities, and drop your judgement and conditioning of what the world is and how it works, this is when you let the magic in. The appearance of The Magician in a reading will herald the upsurge of creative energy and possibilities, and an answer that will solve your dilemma - it has been there all along, but you are only now open to see it.
Image from "Golden Tarot of Klimt" © Lo Scabero, A. Atanassov