Sigils are monograms of thought, for the government of energy, relating to Karma; a mathematical means of symbolising desire and giving it form that has the virtue of preventing any thought and association on that particular desire (at the magical time), escaping the detection of the Ego, so that it does not restrain or attach such desire to its own transitory images, memories and worries, but allows it free passage to the sub-consciousness.

Austin Osman Spare, The Book Of Pleasure