There was a very strong tie which bound the apostle Paul to the brethren in Philippi: he had suffered for them in the stocks, under the lash, and in the nether prison. Sacrifice and suffering for others invest them with a peculiar preciousness.
In a course of lectures at Yale University on pastoral duties, the speaker insisted that love is the only adequate motive to a successful ministry — love of the souls of the people. He was asked, "How can I get this love?" The answer was defective, because it did not recognize the Holy Ghost as the Inspirer of love. The speaker, H. W. Beecher replied "Go to work in earnest for the salvation of souls, and make sacrifices for them, and you will begin to love them." This is true in the case of a pastor already filled with the Spirit of God. In the absence of the Spirit-baptism, self-sacrifice for others, especially the vile and thankless, is a difficult if not impossible achievement. It requires great love to prompt to self-abnegation and voluntary suffering: and this love is of God.
But where such love has been enkindled by the breath of God, it becomes amazingly intensified by our self-denial and patient toil for those who are dead in sin. When they are raised to newness of life by the resurrection power of the Spirit, and are wearing the image of Christ, a bond of love is knit between the pastor and the converts stronger than can be found elsewhere on earth. Hence St. Paul's love for the churches which he had planted amid tribulations, and also his overflowing joy. In the beautiful procession of the fruit of the Spirit, in Gal. 5:22, joy follows love.
Wishing the Philippians to mount up to the highest and purest joy, he prays that their "love may abound yet more and more in knowledge." — chapter 1:9.
There is no such thing in earth or heaven as love in a finite being becoming perfect in volume or degree of strength. The more that men and angels know of God the more they will love him. As knowledge of God is capable of eternal increase, so there will be scope for endless advancement in love and joy.
Mathematicians prove that there is a curve of such a nature (the hyperbola), that it will forever approach a straight line in the same plane, but never touch it. Such a curve is the human soul in its capacity for ever-increasing knowledge and love of God. Among finite aptitudes this talent of eternal growth is a faculty having semi-divine dimensions. In it God's image gleams out most clearly.
The knowledge, in this text, in which love mounts up to higher and higher degrees, is epignosis (ἐπίγνωσις), experimental, certain, and clear. It is the heart of the believer touching the heart of God. The head of pride is always agnostic, the heart of love is always epignostic (not in the dictionary, but signifies knowing certainly).
— adapted from Half-Hours With St. Paul, Chapter 15.