Especially keen became the interest in the skull and brain in which, as Descartes taught, might be found the seat of the soul. Among the earliest of the rough discoveries was that concerned with the localization of special sensory and motor functions of the organism in particular regions of the brain. It was observed that irritation of certain parts of the surface or "cortex" of the brain, in cases where a portion of the skull had been removed, was followed by movement of particular parts of the body, and that individuals who had suffered from injury to certain parts of the brain seemed, on recovery, to be quite their usual selves, except that certain special capacities, as for instance the function of speech, were interfered with or quite destroyed. The unitary soul, described by Descartes as probably having its seat in the pineal gland, now bade fair to disintegrate into various minor faculties, each with its separate brain mechanism and its particular abode in some region of the skull.
The discovery of these elementary facts of brain localization was at once hit upon with zeal by those most interested in the means of foresight into human fortunes. Ignoring the fact that the localized features were simply the control of other parts of the body, as eyes, ears, limbs, speech organs, and the like, these enthusiasts leaped to the conclusion that every trait of character and every mental aptitude, every virtue and vice, ability, interest and capacity, had each its own shelf or pew in the brain area. Moreover, it was taken for granted that the relative development of these various characteristics was indicated by the depressions, projections and proportions of the skull bones. Here was light indeed on the destinies of men, their fitnesses and propensities, their appropriate choice of work and play! The enthusiasm and ardor that went into the elaboration of the new clairvoyance of phrenology would have meant most valuable increase in our knowledge of brain physiology had it been directed exclusively toward further legitimate inquiry. But the urgent desire for control and foresight was too great for practice to keep the slow pace of scientific fact.
Hastily the prophets drew up complicated and minute maps of the surface of the cranium and assigned to each recognizable patch some "faculty" which stood for an important mental or moral trait. Casual examination of the skulls of friends who chanced to possess particularly marked traits to an extreme degree was in some cases relied on to give guidance in the assignment of these patches to the respective traits. In some of the schemes the human traits conceived were so numerous that the bilateral symmetry and functions of the brain were ignored, and the two sides of the skull were assigned quite different functions. Thus arose phrenology, one of the most persistent fallacies of vocational analysis. This movement was founded by Gall and Spurzheim, two physicians and anatomists, in the latter part of the eighteenth century.[1] With the customary naïveté of the medical science of their time, they overestimated the significance of casual observations and fragmentary discoveries, and thus gave impetus to the exaggerated and extravagant claims made by their enthusiastic followers. "Phrenological societies" developed so rapidly and so widely that the movement became relatively independent of the scientific investigations which should have served to qualify and criticize its doctrines. Its propaganda were so vigorous and the practical needs which it promised to satisfy were so insistent, that even today many people hold tenaciously to its dicta. Scores of professionals thrive on their lucrative practice of its dogmas, and university graduates smile in a guilty way when asked, "Do you believe in phrenology?"