Contacts of mobility are those of a changing present, and measure the number and variety of the stimulations which the social life and movements--the discovery of the hour, the book of the moment, the passing fads and fashions--afford. Contacts of mobility give us novelty and news. It is through contacts of this sort that change takes place. Mobility, accordingly, measures not merely the social contacts that one gains from travel and exploration, but the stimulation and suggestions that come to us through the medium of communication, by which sentiments and ideas are put in social circulation. Through the newspaper, the common man of today participates in the social movements of his time. His illiterate forbear of yesterday, on the other hand, lived unmoved by the current of world-events outside his hamlet. The _tempo_ of modern societies may be measured comparatively by the relative perfection of devices of communication and the rapidity of the circulation of sentiments, opinions, and facts. Indeed, the efficiency of any society or of any group is to be measured not alone in terms of numbers or of material resources, but also in terms of mobility and access through communication and publicity to the common fund of tradition and culture. e) _Primary and secondary contacts._--Primary contacts are those of "intimate face-to-face association"; secondary contacts are those of externality and greater distance. A study of primary association indicates that this sphere of contact falls into two areas: one of intimacy and the other of acquaintance. In the diagram which follows, the field of primary contacts has been subdivided so that it includes (x) a circle of greater intimacy, (y) a wider circle of acquaintanceship. The completed chart would appear as shown on page 285. Primary contacts of the greatest intimacy are (a) those represented by the affections that ordinarily spring up within the family, particularly between parents and children, husband and wife; and (b) those of fellowship and affection outside the family as between lovers, bosom friends, and boon companions. These relations are all manifestations of a craving for response. These personal relationships are the nursery for the development of human nature and personality. John Watson, who studied several hundred new-born infants in the psychological laboratory, concludes that "the first few years are the all-important ones, for shaping the emotional life of the child."[118] The primary virtues and ideals of which Cooley writes so sympathetically are, for the most part, projections from family life. Certainly in these most intimate relations of life in the contacts of the family circle, in the closest friendships, personality is most severely tried, realizes its most characteristic expressions, or is most completely disorganized. [Illustration: FIG. 3 A, primary contacts; x, greater intimacy; y, acquaintanceship; B, secondary contacts]