Lo! I put forth my Will, and my Pen moveth upon the Paper, by Cause that my Will mysteriously hath Power upon the Muscles of my Arm, and these do Work at a mechanical Advantage against the Inertia of the Pen. I cannot break down the Wall opposite me by Cause that I cannot come into mechanical Relation with it; or the Wall at my Side, by Cause that I am not strong enough to overcome its Inertia. To win that Battle I must call Time and Pick-axe to mine Aid. But how could I retard the Motion of the Earth in Space? I am myself Party of its Momentum. Yet every Stroke of my Pen affecteth that Motion by changing the Equilibrium thereof. The Problem of every Act of Magick is then this: to exert a Will sufficiently powerful to cause the required Effect, through a Menstruum or Medium of Communication. By the common Understanding of the Word Magick, we however exclude such Media as are generally known and understood. Now then, o my Son, will I declare unto thee first the Nature of the Power, and afterward that of the Medium.