John 1:17 - Ellicott's Commentary On The Whole Bible

The word “for” connects this verse by way of explanation with what has gone before. The Old Testament thought of grace and truth has been already present in John 1:14. The fulness of these divine attributes has been beheld in the glory of the Word. The revelation of them, that is, the removing of the veil which hides the knowable, has been made dependent on the use of the already known. But this is the essence of Christianity as distinct from Judaism; of a spiritual religion developed from within as distinct from a formal religion imposed from without; of a religion of principles, and therefore true for all time and for all men, as distinct from a religion of works, based, indeed, on an eternal truth (the oneness and the righteousness of God) but still specially designed for a chosen people and for a period of preparation. The law was given (from without) by the human agency of Moses. The true grace and truth came into being by means of Jesus Christ. Therefore it is that we receive grace for grace, there being in Him an ever constant fulness of grace, and for the man who uses the grace thus given an ever constant realisation of deeper truth. Note that here, when the divinity and humanity have both been dwelt upon, and in contrast to the historic Moses, the name Jesus Christ first appears. Is there, too, in this union of the human and divine names a reference to the union in Him of the faculty to receive and the truth to fulfil? St. Luke speaks of Him as “increasing in wisdom and stature, and in favour (grace) with God and man” (Luke 2:52; see Note there).