He wishes to show us that it behoves us to love, to hold fast to our love towards Him, and how great a gain we shall have from our union with Him, when He says that He is the Vine, by way of illustration; and that those who are united and fixed and rooted in a manner in Him, and who are already partakers in His nature through their participation in the Holy Spirit are branches; for it is His Holy Spirit Which has united us with the Saviour Christ, since connexion with the Vine produces a choice of those things which belong to It, and our connexion with It holds us fast. From a firm resolve in goodness we proceed onward by faith, and we become His people, obtaining from Him the dignity of Sonship. For according to the holy Paul, He that is joined unto the Lord is one Spirit. As then in other places He has been called the foundation and coping-stone by the voice of the prophets, for upon Him we are built up, ourselves being the stones, living and spiritual stones, into a holy priesthood for a habitation of God in the Spirit, and in no other way are we able to be built up into this, save only if Christ be the coping-stone, so here by a similar reflection He says that He is a Vine, as it were the mother and nourisher of its branches. For we are begotten of Him and in Him in the Spirit, to produce the fruits of life; not the old life of former days, but that which consists in newness of faith and love towards Him.