Some of these authors attempt to separate the physiognomical part of the subject (Chirognomia) from the astrological (Chiromantia); see especially Caspar Schott in Magia naturalis universalis, Bamberg, 1677.
But in its second aspect it touched divination and astrology, of which Galen' says that the physiognomical part is the greater, and this aspect of the subject ' bulked largely in the fanciful literature of the middle ages.
In this passage he deprecates current physiognomical speculations, saying that he might criticize them but feared to waste time and become tedious over them.
A physiognomical study of the Homeric heroes is given by Malalas, Chronogr.
Avicenna also makes some acute physiognomical remarks in his De animalibus, which was translated by Michael Scot about 1270.
The machinery of expression having thus been indicated, the connexion of the physical actions and the psychical state was made the subject of speculation by Herbert Spencer (Psychology, 1855) These speculations were reduced to a system by Darwin (Expression of Emotions, 1872), who formulated and illustrated the following as fundamental physiognomical principles: (1) Certain complex acts are of direct or indirect service, under certain conditions of the mind, in order to relieve or gratify certain sensations or desires; and whenever the same states of mind are induced the same sets of actions tend to be performed, even when they have ceased to be of use.
To the foregoing may be added the following three additional propositions, so as to form a more complete expression of a physiognomical philosophy: (4) Certain muscles concerned in producing these skin-folds become strengthened by habitual action, and when the skin diminishes in elasticity and fulness with advancing age, the wrinkles at right angles to the course of the muscular fibres become permanent.
The preparation in monochrome for this picture, a work of extraordinary power both of design and physiognomical expression, is preserved at the Uffizi, but the painting itself was never carried out, and after Leonardo's failure to fulfil his contract Filippino Lippi had once more to be employed in his place.