The common good is the common temporal happiness of the whole society, duly subordinated to eternal beatitude…This consists principally in the good of human virtue, both intellectual and moral. For the perfection or happiness of man lies in the exercise of virtuous activity, conformed to his rational nature.

Thus, the common good lies essentially in those virtues which brings about the perfect human life, both active and contemplative; integrally in the other arts and sciences; consequentially in the peace and common friendship which naturally flow from such virtuous life; instrumentally in some abundance of exterior goods, which must be used in a well constituted society.

        (Benedict Merkelbach O.P. Summa Theologiae Moralis, II, 265)