IV. 4. 40
(Armstrong Selection and Translation from the Enneads)
How do magic spells work? By sympathy, and by the natural concord of things that are alike and opposition of things that are different, and by the rich variety of the many powers which go to make up the life of the one Living Creature. For many things are drawn and enchanted without any other contrivance. The true magic is the ‘ Love and Strife’ in the All. This is the primary wizard and enchanter, from observing whom men come to use philtres and spells on each other. For because desire is natural and things that cause desire attract each other, there has grown up an art of attraction by desire through magic, used by those who add by magic touches various natures designed to draw different people together and with a force of desire implanted in them: they join one soul to another, as if they were training together plants that grow in different places. They use as well figures with power in them, and by putting themselves into the right postures they quietly bring powers upon their patients through their participation in the unity of the universe. For if anyone put a magician outside the All, he could not draw or bring down by attractive or binding spells. But now, because he does not operate as if he were somewhere else, he can work with a knowledge of where one thing is drawn to another in the Living Creature. And the soul too is naturally drawn by the tune of a magic chant or a particular intonation or posture of the magician — for these things attract, as pitiable figures and voices attract: for it is not the will or reason which is charmed by music, but the irrational soul, and this kind of magic causes no surprise; people even like being enchanted, if this is not actually what they demand from the musicians. And we must not think that other kinds of prayers either are freely and deliberately answered. For people charmed by spells do not act with free deliberation, nor, when a snake fascinates a man, does the man understand or perceive what is happening, but he knows only afterwards that he has had the experience; his ruling intellect, however, remains unaffected. When a man prays to anything, some influence comes from it upon him or upon another: the sun, or another star, does not hear his prayer.