features of
"social" and "living bodies," noting likeness and differences,
particularly with reference to complexity of structure, differentiation
of function, division of labor, etc., Spencer gives a perfectly
naturalistic account of the characteristic identities and differences
between societies and animals, between sociological and biological
organizations. It is in respect to the division of labor that the
analogy between societies and animals goes farthest and is most
significant.

This division of labour, first dwelt upon by political
economists as a social phenomenon, and thereupon recognized by
biologists as a phenomenon of living bodies, which they called
the "physiological division of labour," is that which in the
society, as in the animal, makes it a living whole. Scarcely
can I emphasize enough the truth that in respect of this
fundamental trait, a social organism and an individual organism
are entirely alike.[29]

The "social aggregate," although it is "discrete" instead of
"concrete"--that is to say, composed of spatially separated units--is
nevertheless, because of the mutual dependence of these units upon one
another as exhibited in the division of labor, to be regarded as a
living whole. It is "a living whole" in much the same way that the plant
and animal communities, of which the ecologists are now writing so
interestingly, are a living whole; not because of any intrinsic
relations between the individuals who compose them, but because each
individual member of the community, finds in the community as a whole, a
suitable milieu, an environment adapted to his needs and one to which he
is able to adapt himself.

Of such a society as this it may indeed be said, that it "exists for the
benefit of its members, not its members for the benefit of society. It
has ever to be remembered that great as may be the efforts made for the
prosperity of the body politic, yet the claims of the body politic are
nothing in themselves, and become something only in so far as they
embody the claims of its component individuals."[30]

In other words, the social organism, as Spencer sees it, exists not for
itself but for the benefit of the separate organs of which it is
composed, whereas, in the case of biological organism the situation is
reversed. There the parts manifestly exist for the whole and not the
whole for the parts.

Spencer explains this paradoxical conclusion by the