Magic is the harnessing of the energy in the mind, which I shall refer to as Astral energy from now on. This energy is generated by all things, especially living minds. It flows into and out of our bodies, and whether you realise it or not, you use it all the time. But conscious, controlled use of astral energy is very difficult. And there's also not a great deal that a human can do with the energy he possesses; astral energy has little effect on the real world. What other worlds are there? Many! They're known as the Astral Planes, and they are literally different planes of reality.
This is an important point; it is essential that you realise that when I refer to the Astral planes, I do not mean the 'other dimensions' beloved of scientists; those are based on the same 'rules' our own is, composed of the same substances, and so on. The Planes are NOTHING like this; they are not, strictly speaking, dimensions, but different aspects of this one. They are composed of pure Astral energy. The plane closest to this one is, in fact, indistinguishable from the real thing, and this is where the people who have 'out of body' experiences go, which is why they think they're still in the real world. You can NEVER physically enter the Astral plane, though the denziens of the Astral plane can, in a way, physically enter the real world. It is, quite literally, a world made of thought, and its nature is a reflection of our own minds.
Why can't we enter, you may wonder. If it's a place, we can go there. Well, much as I hate to say this, you are wrong. We can only enter the Astral plane by sending our own Astral bodies into it. Our physical forms can only inhabit the physical world. Why is this? Well, put it this way; could you ever 'enter' the world you see in a Virtual Reality game? No. Of course not. And in a way, that is all the Astral planes are; an artifical, CREATED world. And this is what I mean:
Magic is based entirely on perception and analogy. Everything that we do is, though you may try and dispute this. But consider; Red. The colour. Conjure it up in your mind, a red shape. Look around you; you will probably see something red. So, red exists independantly of whether or not you are looking at it? No. An energy wave with a particular frequency exists outside your perception, but the COLOUR red exists only in your own mind. Colour exists only in your mind, not in the real world. But, since you PERCEIVE it as red, it IS red. Because, to humans, perception and reality are identical. One and the same. The same with sound; imagine the sound of someone playing the piano. It sounds pleasant, all the notes in harmony, playing a recognisable tune. But in reality, there is no such thing as sound. There is only pressure differences in the air, that you PERCEIVE as meaningful sound.
You may say this is nitpicking, but it is not; it is fundamental to your understanding of magic. Your brain recieves nerve impulses, which it assembles to form a meaningful picture, which it gives your mind. Your mind makes a decision, and wills the body to take action. This willed command is passed to the brain, which turns it into a set of nervous impulses, that the body can understand. You do NOT, you CAN not, make those nerve impulses work directly; mind to body.
For example; Blink. A simple operation, you just 'push' your eyelids down, yes? No. Muscles, you see, CANNOT push; they are only capable of pulling. Blinking is an intricate action requiring well over a hundred muscles working in perfect co-ordination. But to you, it is a simple 'push' that requires no thought at all. This is because all you need do is 'will' a thing to happen, and your brain takes care of the how. And in a way, that is what magic does; you 'will' something to happen, and it does, not because willpower itself can affect the universe, because it can't, but because your will was changed from internal thought to energy capable of affecting the world by your Astral body. because that is what magic is; your will, focussed through your Astral self, affecting the world, whether it is the real or Astral world.
What does this have to do with the nature of Astral planes? This: They are not a place, they are simply percieved as one. They have as much substance as a dream, and this is because that is precisely what they are; when you dream, your mind is dwelling in the Astral planes. The Astral planes are living energy translated by our minds into forms can perceive, they are not dimensions we can enter. Clear?
So, now you know what magic is, what can you do with it?