“The common good is greater not because it includes the singular good of all the singulars; in that case it would not have the unity of the common good which comes from a certain kind of universality in the latter, but would merely be a collection, and only materially better than the singular good. The common good is better for each of the particulars which participate in it, insofar as it is communicable to the other particulars; communicability is the very reason for its perfection. The particular attains to the common good considered precisely as common good only insofar as it attains to it as to something communicable to others. The good of the family is better than the singular good not because all the members of the family find therein their singular good; it is better because, for each of the individual members, it is also the good of the others. That does not mean that the others are the reason for the love which the common good itself merits; on the contrary, in this formal relationship it is the others which are lovable insofar as they are able to participate in this common good.
Thus the common good is not a good other than the good of the particulars, a good which is merely the good of the collectivity looked upon as a kind of singular. In that case, it would be common only accidentally; properly speaking it would be singular, or if you wish, it would differ from the singular by being nullius. But when we distinguish the common good from the particular good, we do not mean thereby that it is not the good of the particulars; if it were not, then it would not be truly common.” (On the Primacy of the the Common Good, De Koninck)