In his famous Nicomachean Ethics, Aristotle recognizes that we human beings aim at attaining a veritable panoply of goods. This panoply includes goods as diverse as life, friends, comfortable shoes, a steak dinner, fine wine, health, the virtues, enough money to meet one's needs, medicine when one is ill, sufficient exercise, and so forth. All these things we deem desirable and connected with or constitutive of our complete good which we commonly call "happiness." At the same time, Aristotle sees clearly that not all human goods are on the same level. Some, he says, are more divine or God-like than others.
To help make this evident, we can divide up all human goods into those goods which can be enjoyed by many persons at a given time and those goods which cannot be so enjoyed. Under those goods which cannot be enjoyed my many persons simultaneously fall things such as eyeglasses, hats, shoes, and toothbrushes. If these goods are to be utilized or enjoyed by many persons, these persons must take turns doing so. Different from these goods are things like Thanksgiving turkeys, houses, and oratorios such as Handel's Messiah. For each one of these goods can be enjoyed, and very often is enjoyed, by many persons at the same time. Such goods are sometimes called "common goods" in contradistinction to "private goods" such as eyeglasses, hats, and so forth.
It is essential to note, though, that the common goods just described are common only up to a point. The Thanksgiving turkey can be enjoyed by only so many people and each person sharing in the feast merely gets a part of the whole turkey. In a similar way, although it is possible for each person who lives in a house to enjoy the whole house as, in some sense, his own, and although whoever is in the concert hall listening to Handel's Messiah can enjoy the whole oratorio as his own good, it is also true that only so many people can live under one roof and only so many people can fit in the concert hall.
More common than these material common goods are spiritual common goods. For any spiritual common good may be enjoyed or possessed at one and the same time, in its entirely, by a potentially infinite number of persons. To exemplify the nature of these more common or more universal common goods, we need only think of this basic truth of geometry: every triangle is such that any two of its sides added together are longer than the remaining side. This one truth, which perfects our intellects when we understand it, can be known simultaneously and in its entirety by a potentially infinite number of persons and each of them can possess this truth as his own intellectual good. Thus, this common good is more common than all of the aforesaid material common goods put together.
Of course, the most exalted spiritual common good of all is God Himself. As uncreated infinite Goodness Itself, God is the extrinsic common good of the entire created order and of every creature contained therein. Further, He is the cause of all created goods, whether they be spiritual common goods, material common goods, or simply private goods. In fact, all these created goods are but faint shadows or reflections of the Divine Goodness which is God Himself.
Given the inexhaustibility of spiritual common goods described above, and especially of God Himself, the following text from Fr. Reginald Garrigou-Lagrange may serve as an appropriate way to end our reflections here:
Such are the inexhaustible riches of the spirit that they can be the property of all and yet satisfy the desires of each. Indeed, only then do we possess a truth completely when we teach it to others, when we make others share our contemplation; only then do we truly love a virtue when we wish others to love it also; only then do we wholly love God when we desire to make Him loved by all.