A book full of esoteric knowledge. White magic, green magic, blue magic, red magic, and golden magic. Pythagoras, Leonardo da Vinci, Isaac Newton and René Descartes are just a few examples of the most important scholars who believed in esotericism and practiced magical arts. Many of Shakespeare's works are delicately interwoven with magical beliefs. Sigmund Freud was notoriously superstitious, and Carl Gustav Jung made a study of magic, so serious and profound, that many of his detractors accused him of dabbling excessively in mysticism.