There are many people who say that when one calls a spirit, it isn't really the spirit who comes, but one of its associates, who assumed the spirit's shape and speaks for it. Then there are people who say that's not true and the intended spirit does show up. I have a theory that reconciles both points of view.
I'll give, as an example, the god Zeus. When a magician invokes Zeus, he sends energy to the god, in the form of words, emotions, faith, concentration, etc (everything he puts into the invocation). That amount of energy is received by Zeus and, naturally, he responds by sending the energy back to the magician, only this time the energy is not as the magician sent it, but transformed into his own (Zeus's) energy. The amount of energy is the same, only now it is transformed into that of Zeus and has the form and attributes of Zeus. But it isn't really Zeus, just a fraction of him.
An invocation can have many forms. One of the best, I learned, is a prose or poetry that describes the god in detail. The more of that god is described, the more of him is "accessed"/invoked, so to speak. But it is not the entire god, only the amount of force that the magician sent to him and received back. The actual Zeus is conscious and living, like us. And he has a lot of important work to do. Why would he come to just any magician who invokes him? Naturally, he would only send a fraction of his energy. Now this doesn't mean that, if he sends only his energy, the magician can't work with that. The energy of a spirit is intelligent, has a personality, a mind of its own, it can be worked with. But it is not to be confused with the actual, conscious and individual spirit.
An actual, individual god, can't be in multiple places at once. But his energy can, which is why many magicians from different parts of the world can invoke him at the same time. It is their energy, transformed into that of the god.
Now to invoke the entire god, one would have to do it by devotional life-long practice. One would have to continuously pray to that god and invoke him, day and night, make offerings, sincerely ask for initiation and knowledge of that god, etc. Ultimately, if the right amount of devotion and faith is put into the invocation, years later, the entire, actual god, will show up and the magician's life will radically change. A real god showing up would be one of the highest forms of initiation.
So in the absence of real devotion and life-long work, a magician only works with the energy of the spirit, not with the entire spirit.
What do you think about this theory?