Morel d'Arleux's Système de Lebrun sur la Physionomie   (1 : 3) P. 355x378mm., S. 590x430mm.

Plate 1 Human heads seen in front and profile views, drafted for the demonstration of Le Brun's system

Morel d'Arleux's explanation goes roughly as follows:

Figure 1A (centre) The horizontal line runs through each corner of the eye, forming an angle of which the opening gives the measure of the genius of men, ... those of whom nature has tempered the passions by a soft moderation in according them the continual use of reason and the habitual exercise of all amiable virtues.

Figure 1B (right) The raised inner corners ... designate beings gifted with genius, moved by noble and generous passions, and destined by their fine deeds to deserve immortality.

Figure 1C (left) Individuals subject to shameful, detestable, or atrocious passions are recognizable by the lowering of the inner corner.