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 reflection that in social organisms sentience is not localized as it is in biological organisms. This is, in fact, the cardinal difference between the two. There is no _social sensorium_.
In the one (the individual), consciousness is concentrated in a small part of the aggregate. In the other (society), it is diffused throughout the aggregate: all the units possess the capacities for happiness and misery, if not in equal degrees, still in degrees that approximate. As then, there is no social sensorium, the welfare of the aggregate, considered apart from that of the units, is not an end to be sought. The society exists for the benefit of its members; not its members for the benefit of the society.[31]
The point is that society, _as distinct from the individuals_ who compose it, has no apparatus for feeling pain or pleasure. There are no _social_ sensations. Perceptions and mental imagery are individual and not social phenomena. Society lives, so to speak, only in its separate organs or members, and each of these organs has its own brain and organ of control which gives it, among other things, the power of independent locomotion. This is what is meant when society is described as a collectivity.