ch is transmitted from the older to
the younger generations. Through the medium of tradition, including in
that term all the learning, science, literature, and practical arts, not
to speak of the great body of oral tradition which is after all a larger
part of life than we imagine, the historical and cultural life is
maintained. This is the meaning of the long period of childhood in man
during which the younger generation is living under the care and
protection of the older. When, for any reason, this contact of the
younger with the older generation is interrupted--as is true in the case
of immigrants--a very definite cultural deterioration frequently ensues.

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