PERFECTION IS UNDERSTOOD TO MEAN, BOTH THE LOVE OF GOD, AND THE LOVE OF OUR NEIGHBOUR
THE perfection of the spiritual life may be understood as signifying principally perfection, as it regards charity. Now there are two precepts of charity, one pertaining to the love of God; the other referring to the love of our neighbour. These two precepts bear a certain order to each other, proportioned to the order of charity. That which is chiefly to be loved, by charity, is the Supreme Good, which makes us happy, that is to say, God. In the next place, we are, by charity, to love our neighbour, who is, by certain social bonds, united to us, either by the anticipation of beatitude, or in the enjoyment of it. Hence, we are bound in charity to love our neighbour, in order that, together with him, we may arrive at beatitude.
Our Lord establishes this order of charity in the Gospel of St. Matthew (xxii. 37), where He says, "Thou shalt love the Lord thy God with thy whole heart and thy whole soul and thy whole mind. This is the first and greatest commandment; and the second is like to this: Thou shalt love thy neighbour as thyself." Thus, the perfection of the spiritual life consists, primarily and principally, in the love of God. Hence the Lord, speaking to Abraham, says, "I am the Almighty God; walk before me and be perfect" (Gen. xvii. 1). We walk before God, not with bodily footsteps, but with the affections of the mind. The perfection of the spiritual life consists, secondarily, in the love of our neighbour. Therefore when our Lord had said, "Love your enemies" (Matt. v. 44), and had added several other precepts regarding charity to our neighbour, He concluded by saying, "Be ye therefore perfect, as also your heavenly Father is perfect."