Crowley defined magick as `` the science and art of causing change to occur in conformity with the will . '' By this , he included ordinary acts of will as well as acts of ritual magic . The British occultist Aleister Crowley , chose the spelling to differentiate the occult from stage magic and defined it as `` the Science and Art of causing Change to occur in conformity with Will '' , including both `` mundane '' acts of will as well as ritual magic .