Here is indeed a most confused mass of fact and fancy which finds credence in varying degrees on diverse occasions. Seldom has it been analyzed into the definite types of material which it really contains, and its evaluation is commonly left to the haphazard opinion of each individual. There is no doubt that we all tend to form our opinion of a stranger's probable characteristics partly on the basis of these physiognomic, physical, and sartorial factors. To what degree can these items be formulated so as to afford reliable criteria in the analysis of personality, as in the case of vocational selection and employment? We may perhaps best answer this question by noting the various sources of the belief in the validity of physiognomic and similar signs.
1. It is first of all true that many of these marks are the result of habitual activity, and in so far as they originate in the expression of a trait, they may be said to be signs of it. That the studious come to be round-shouldered, the cheerful to have smooth countenances, the guilty to have furtive eye-movements, may well be expected. But it is quite another thing to reverse the proposition and to take stooped shoulders as a universal sign of academic interests, dimples as a sign of guilelessness, and nystagmus as the symptom of a criminal past. It is, however, often safe to use these traits as reliable signs of the established general habits and attitude which they express. We have all done this since earliest childhood; yet any attempt to classify formally the signs and effects of habit and constant expression would be pedantic. Unfortunately for the purposes of vocational guidance of youth, these expressions require for their formation habits of fairly long standing, and the critical period for psychological guidance is likely to be passed long before these settled habits have set the features into their identifiable molds.
Somewhat more hopeful is the reliance on expressive movements as indicative of passing and transient emotional states and attitudes. Not easily can we conceal from the astute observer the momentary passion that may be stirring us. Prolonged intimate acquaintance with an individual's emotional experiences and expressions may in time reveal to such an observer the deeper lying and more permanent affective trends, the moods and sentiments which indicate what we are accustomed to call the temperament of the individual. Insight into the nature of these expressive movements is one of the useful things to be derived from long and patient study of human nature, both at first hand and through the classical descriptions of emotional expression. The more one observes and the more individuals he observes, the more he is impressed with the final variety and informal complexity of these expressive movements, and their dependence on a vast detail of circumstance, which again forbid rule-of-thumb formulation.