But when a difficulty arises, see how he begins to knit his brow. It is the difficulty which has arisen, and not the course of his thoughts, that has produced this muscular reaction.
The movement is similar to what occurs in the case of any difficulty to overcome, as, for instance, the threading of a needle.
Consequently the wrinkles of thought are the wrinkles of the fatigue of thought.
The mystics, who are purely contemplative thinkers, and not solvers of difficulties, have a forehead without lines. Similarly in art, the faces of the Madonna or of the Saints have an intense expression of thought in their gaze, but the serene countenance shows neither contractions nor lines.
De Sanctis[46] has made some interesting observations regarding the facial expression of the mentally deficient. They have a singular difficulty in contracting the frontal muscle even at the age of eleven or twelve years; even when urged by example and command, they frequently do not succeed in contracting the forehead. Labial expression, on the other hand, is much more developed, and frequently attention is indicated by a contraction of the orbicular muscle of the lips into a circle; and surprise is shown in the same way.
In general, however, what characterises the face of the imbecile, the idiot, the epileptic, is its immobility: hypomimia or amimia.
There are, however, frequent cases of cerebrophlegia (a progressive malady of the brain occurring during the early years of childhood), in which exaggerated contractions of the face occur as the result of the least mental effort. The French give the name of grimaciers to children who show such symptoms; from pathological causes they exhibit a hypermimia that transforms their facial expressions into grimaces. Furthermore, there are certain degenerate children in whom the muscular reactions do not correspond to the normal expression of their feelings; for example, they exhibit sorrow when they mean to show attention, etc. In such cases the play of the opposite and contradictory facial muscles has become perverted: dismimia.
One of the most frequent occurrences among the abnormal is asymmetry of the facial expressions; the muscles contract more on one side of the face than on the other. This symptom, however, in a mild degree, is met with also in normal persons.
From what has been said, it is evident that for the examination of the face we must depend, if not exclusively, at least far more upon anthroposcopy than upon anthropometry; and since the minute description required is too difficult and too lengthy a task, especially as regards the facial expressions (which are so characteristic of the individual) it is necessary in pedagogic anthropology to resort to photography.
The instantaneous photograph, in all progressive countries, is already within the reach of mothers. It ought also to form part of the equipment of our schools.