The knowledge of God is the supreme mental good, and to know God is the supreme mental virtue. For God is the supreme subject of the understanding, and therefore to know or understand God is the supreme virtue of the mind. But to us nothing can be either good or evil unless it has something in common with us. Nothing can be reckoned good except that which is in harmony with our nature, and nothing can be reckoned evil except what is contrary to our nature, but men cannot be said to agree in nature when they are subject to passions. We only act in harmony with the dictates of reason when we agree in nature with others.
Men are most useful to each other who are mutually ruled by the laws of reason.
Yet men are seldom disposed to solitude, but answer generally to the familiar description of man as a social animal, for they know that the advantages preponderate over the disadvantages of social life. They find by experience that by mutual aid and co-operation they can the more easily secure what they need. A man who seeks after virtue will desire others to do so, and this desire will increase in proportion to the increase of his knowledge of God. This is in accordance with reason, which is the operation of the mind according to the essence of the mind, that essence being knowledge, which involves the knowledge of God. The greater the knowledge of God involved in the essence of the mind, the greater will be the desire that others may seek after the same virtue which the man seeks for himself.