Psychology

The study of the soul predates the discipline that bears its name. From Aristotle's De Anima through the medieval dream books and Renaissance treatises on the passions, the question of what the psyche is and how it operates has wound through philosophy, medicine, and religion for two millennia. This collection traces that history from its ancient and early modern roots through the emergence of psychology as a modern science in the nineteenth century.

The founding generation worked across what now seem like distant fields. Gustav Theodor Fechner's Elemente der Psychophysik (1860) established the mathematical measurement of sensation, but he also wrote Nanna, oder über das Seelenleben der Pflanzen on the soul-life of plants, and Zend-Avesta on cosmic consciousness. William James's Principles of Psychology (1890) defined the field for the English-speaking world, while his Varieties of Religious Experience explored mystical states with the same empirical rigor. Franz Anton Mesmer's work on animal magnetism opened the door to hypnosis and the unconscious decades before Freud. Pierre Janet's L'automatisme psychologique mapped the dissociative processes that Jung would later reinterpret as autonomous complexes. Christian Wolff's Psychologia empirica and Psychologia rationalis — the works that gave the discipline its name — stand alongside Carl du Prel's Philosophie der Mystik, which treated dreams, somnambulism, and clairvoyance as legitimate objects of psychological inquiry.