Magick Defined
In brief Crowley defines Magick as follows in his book Magick in Theory and Practice.
1) Every intentional act is a Magickal act.
(Illustration: See "Definition" above.)
By "intentional" I mean "willed". But even unintentional acts so seeming are not truly so. Thus, breathing is an act of the Will to Live.
14) Man is capable of being, and using, anything which he perceives, for everything which he perceives is in a certain sense a part of his being. He may thus subjugate the whole of the Universe of which he is conscious to his individual Will.
(Illustration: Man has used the idea of God to dictate his personal conduct, to obtain power over his fellows, to excuse his crimes, and for innumerable other purposes, including that of realizing himself as God. He has used the irrational and unreal conceptions of mathematics to help him in the construction of mechanical devices. He has used his moral force to influence the actions even of wild animals. He has employed poetic genius for political purposes.)
25) Every man must do Magick each time he acts or even thinks, since a thought is an internal act whose influence ultimately affects action, though it may not do so at the time.
(Illustration: The least gesture causes a change in a man's own body and in the air around him; it disturbs the balance of the entire Universe, and its effects continue eternally throughout all space. Every thought, however swiftly suppressed, has its effect on the mind. It stands as one of the causes of every subsequent thought, and tends to influence every subsequent action. A golfer may lose a few yards on his drive, a few more with his second and third, he may lie on the green six bare inches too far from the hole, but the net result of these trifling mishaps is the difference between halving and losing the hole.)
Bibliography
Crowley, Aleister. Magick in Theory and Practice. Secaucus, New Jersey: Castle Books, 1991.