e locality constitutes an
essential point of attachment for the further persistence of the group.
But it is only one such element, for there are groups that get along
without a local substratum. On the one hand, there are the very small
groups, like the family, which continue precisely the same after the
residence is changed. On the other hand, there are the very large
groups, like that ideal community of the "republic of letters," or the
other international associations in the interest of culture, or the
groups conducting international commerce. Their peculiar character
comes from entire independence of all attachment to a definite locality.

b) _Continuity through blood relationship._--In contrast with this
more formal condition for the maintenance of the group is the
physiological connection of the generations. Community of stock is not
always enough to insure unity of coherence for a long time. In many
cases the local unity must be added. The social unity of the Jews has
been weakened to a marked degree since the dispersion, in spite of their
physiological and confessional unity. It has become more compact in
cases where a group of Jews have lived for a time in the same territory,
and the efforts of the modern "Zionism" to restore Jewish unity on a
larger scale calculate upon concentration in one locality. On the other
hand, when other bonds of union fail, the physiological is the last
recourse to which the self-maintenance of the group resorts. The more
the German guilds declined, the weaker their inherent power of cohesion
became, the more energetically did each guild attempt to make itself
exclusive, that is, it insisted that no persons should be admitted as
guildmasters except sons or sons-in-law of masters or the husbands of
masters' widows.

The physiological coherence of successive generations is of incomparable
significance for the maintenance of the unitary self of the group, for
the special reason that the displacement of one generation by the
following _does not take place all at once_. By virtue of this fact it
comes about that a continuity is maintained which conducts the vast
majority of the individuals who live in a given moment into the life of
the next moment. The change, the disappearance and entrance of persons,
affects in two contiguous moments a number relatively small compared
with the number of those who remain constant. Another element of
influence in this connection is the fact that human b