Phrenology

Phrenology, a science popular from the early to the mid-nineteenth century, was dedicated to the discernment of one's character or traits of personality from reading—that is, feeling the shape and size of—the bumps on one's skull. As formulated by the German physician and anatomist Franz Josef Gall (1758–1828) and as popularized by his student and follower Johann Gaspar Spurzheim (1776–1832), phrenology was based on five main tenets: (1) the brain is the organ of the mind—mental activity is produced by the structure and function of the brain, not through some spiritual or immaterial process; (2) the brain is not unitary but a congeries, or collection, of separate faculties; (3) these faculties are localized in different regions of the brain; (4) the activity of a mental faculty determines the size of the brain organ that represents it; and (5) the skull ossifies over the brain during infant development, so that an external examination of the size and shape of the bumps on the skull will reveal the size of the underlying brain organs. A staunchly materialistic doctrine, phrenology held that each mental faculty, envisioned by Gall as an innate instinct, produced a striking behavior or characteristic. Each innate mental faculty was in turn produced by its underlying brain organ, whose size depended on its activity and which could be revealed by its corresponding cranial bump.