Generally speaking, then, dictionaries define genius as a superior or superlative degree of intellectual capacity, and avoid claiming it for any concept of an added, different, or abnormal element in human faculty.
CONCEPTS OF GENIUS
As a manifestation of abnormal psychology. A number of thinkers in fields allied to psychology have laid emphasis upon a supposed connection between genius and nervous instability or insanity. This idea is embodied in the statement by Pascal: "L'extrême esprit est voisin de l'extrême folie." Lamartine refers to "la maladie mentale qu'on appelle génie." Lombroso (10) is perhaps the most widely quoted among those who have held or who hold this point of view.
As constituting a different species. The idea has been expressed by thinkers other than professed psychologists—and at times by psychologists themselves—that men of genius are a separate species, partaking of qualities not shared in any degree by persons at large. This concept is at one with that which would regard the idiot and the imbecile as distinct in kind, not in degree only, from the mass of mankind. Genius would thus be not merely more of the same but a different sort altogether. Thus Hirsch (7) specifically declares:
The genius differs in kind from the species, man. Genius can be defined only in terms of its own unique mental and temperamental processes, traits, qualities, and products. Genius is another psychobiological species, differing as much from man, in his mental and temperamental processes, as man differs from the ape.
As a hypertrophied and highly specialized aptitude for specific performance. The thought has been advanced that intellectual genius is a matter of specialization; that the mind of a genius will not, typically, work on all data with superior results, but that it is adapted only or primarily to certain kinds of intellectual performance. In other words, the genius is thought to lack general ability. A recent statement by Carrel (2) seems to express in part at least this theory:
There is also a class of men who, although disharmonious as the criminal and the insane, are indispensable to modern society. They are the men of genius. They are characterized by a monstrous growth of some of their psychological activities. A great artist, a great scientist, a great philosopher, is rarely a great man. He is generally a man of common type, with one side over-developed.
As a combination of traits. Galton (6) thought of genius as that which qualifies a person for eminence, and he believed that achieved eminence must be founded on a combination of no less than three essentials. He wrote:
By natural ability I mean those qualities of intellect and disposition which urge and qualify a man to perform acts that lead to reputation. I do not mean capacity without zeal, nor zeal without capacity, nor even a combination of both of them, without an adequate power of doing a great deal of very laborious work. But I mean a nature which, when left to itself, will, urged by an inherent stimulus, climb the path that leads to eminence, and has strength to reach the summit . . . one which, if hindered or thwarted, will fret and strive until the hindrance is overcome, and it is again free to follow its labour-loving instinct. It is almost a contradiction in terms to doubt that such men will generally become eminent.
Again, Galton says: