The theory of the common good completes Green's moral theory. So far we have discussed the formal and the substantive descriptions of morality as presented in the first two chapters of Book III of the Prolegomena. The theory of the common good is developed in the third and fourth chapters of Book III and they will be the object of discussion in this chapter. We shall see that the full realisation of the individual's capacities is only one side of the moral ideal, the other being the pursuit of the well-being of others. In this sense the concept of the common good rounds up Green's moral theory. It gives further specification of both the formal and the substantive definitions of moral behaviour. As with his theory of morals, Green's common good theory contains two legitimate but distinguishable senses of the common good. In its first sense the common good should be understood as the principle of personal moral growth. In this sense it represents a theory laying down the formal conditions of moral action. It develops further the already given formal definition of morality as an activity performed in a self-disinterested way. The second sense is the common good as the society of equals. It expands the already given substantive definition of morality as the state of human perfection.