Why not to use explanations for magic that actual "thaumaturgical" traditions used? Basically that reality is a projection of our minds, and sufficiently concentrated and focused minds can change reality in ways that is perceptible for others too, and thus magical rituals and chanting and spells are ways to concentrate and focus the mind. You can also give it a neat theistic angle, such as when god made man in his own likeness it meant also giving him some of his creative power, to make things ex nihilo just with his mind.