Phrenology is a system of measuring a person's character and intelligence by feeling the bumps and depressions on his skull. Phrenology is based on the work and theories of Franz Joseph Gall, a German anatomist of the late 18th and early 19th centuries. The term "phrenology" was adopted by Gall's student and coworker, Johann Spurzheim. According to Gall's theory the brain was composed of many organs, or areas. Each organ was thought to be the center of a particular character or intellectual trait, and the strength or weakness of each trait was determined by the size of the organ in which that trait was centered. For example, Gall believed that benevolence arose from an area of the brain at the top-front of the head. Behind the area for benevolence was the area for reverence. By feeling the size and shape of the skull covering these areas, Gall believed he could tell how benevolent a person was and how reverent he was. Many other traits of character and intelligence could also be measured by feeling other bumps and depressions on a person's skull.
Gall's theories enjoyed great popular appeal, largely due to the writings and lectures of his coworker from about 1817 to Spurzheim's death in 1850. The two men made charts showing the different areas of the skull and the different qualities centered in each area. The charts were widely displayed. For a number of years there were many phrenological societies and publications in Europe and in the United States. Soon, phrenology came to include a wide variety of beliefs dealing not only with brain structure, but also with such subjects as psychology, social philosophy, and the treatment of the mentally ill.
Later phrenologists taught that a person is born with a certain set of mental abilities, which can be measured and changed. They also taught that character traits and mental abilities increase through exercise and that a person can consciously develop his virtues and talents and weaken his vices and disabilities. Phrenologists claimed to be able to show people how to be happy, how to choose a profession, how to select a mate, and how to raise children. They also claimed to be able to diagnose and cure insanity and to reform criminals. Such ideas had little to do with Gall's original theory of phrenology.
However, even the original theory has never been accepted by scientists, and today, the practice of phrenology is considered a form of fraud. It has no scientific basis. The shape of the skull does not correspond to the shape of the brain underneath it, and there is no evidence that particular traits are localized in specific areas of the brain. The phrenologists were correct, however, in believing that the brain is the organ of mind, as Gall called it. It is also true that different parts of the brain are involved in different physiological functions and, in this way, may give rise to specific mental traits. However, the mind is so complex that it cannot be easily broken down into specific component parts.