Do what thou wilt shall be the whole of the Law
Not long ago I was meditating on the mixing of the planes. I was told long ago to be careful not to mix the planes. At the time, it seemed a reasonable perception. After all, an example would be if you tried to purchase a gallon of milk with Monopoly game money. The paper money is good for its plane of use, that is, the game of Monopoly. Yet to try to purchase a gallon of milk in a store with fake money would be a confusion of the planes. Only real money would be accepted. You have thus mixed the real world of capitalism with the imaginary world of a game of Monopoly.
The true purpose of learning not to mix the planes is to cleanly look at the planes so they can be 'mixed' by an act of will to create change. Magick is then, ironically, an operation of the mixture of the planes by an act of will. We keep the planes separate by following our correspondences in Liber 777 to build a ritual of some operation and then totally contradict our first principle by using physical objects to manipulate non-material objects. A delightful paradox! We mix the planes by, say, using a physical object like a green Ankh to attract the attention of the Goddess Ahathoor to assure the love of our life to magically appear. Other examples of how magick mixes the planes is using physical sex to awaken energies in our aura to cause change.
Mixing the planes during communication between Thelemites is very common. Much of this is concerning ego based problems. We have the type of Thelemite who mixes the planes of another Thelemite by some accusation or speculation based on some petty irritation. In this particular example, we have an accusation instead of a real fact. It is as if such people make something up, then become convinced that it is a fact. They are then mixing the planes of what is real and what they have made up. It is as if they confuse their hatred based on the way their ego is reacting on the rival and become completely out of touch with reality.
We have then, two ways to mix the planes. One is a contradiction that is a dispersion. The other is a harmony that is balance of energy. We have harmonious planes of existence such as a physical magician controlling the forces of nature, or inharmonious planes of existence such as a a physical magician who is controlled by a mechanical current of the dead aeon. In the latter case, the physical magician has failed to perceive how energy is controlled and mixes the planes by using a improper formula.
In conclusion, we see that the proper key to the problems of mixing the planes is volition and harmony. And remember that in the Magus card in the Tarot he is juggling his weapons, the planes of the magician being symbolized as absolutely perfect and in harmony.
Love is the law, love under will