" As the medieval historian Richard Kieckhefer notes, the people of medieval Europe thought of magic as rational for two reasons: “first of all, that it could actually work (that its efficacy was shown by evidence recognized within the culture as authentic) and, secondly, that its workings were governed by principles (of theology or of physics) that could be coherently articulated. "

― Michael Shermer , The Moral Arc: How Science and Reason Lead Humanity toward Truth, Justice, and Freedom