Herman Ridderbos on John 1:17 (“For the law was given through Moses; grace and truth came through Jesus Christ.”) in The Gospel of John, 57-58:
“The contrast with Moses (if indeed that, rather than a simple juxtaposition, is what we have here) is not straightforward. We need to ask whether all of vss. 14-18 must be read against the background of the story of the giving of the law in Exodus 34. One can advance several arguments in support of this view. Vs. 17 explicitly mentions the giving of the law. Exodus 34 mentions God’s ‘grace and truth’ and explicates it as ‘slow to anger, abounding in steadfast love and faithfulness …’ (vss. 6f.). Exodus tells of Moses’ desire to ‘see’ God’s face, just as Jn. 1:18 mentions ‘seeing’ God. Though most interpreters acknowledge the connection with Exodus 33 and 34 at least in regard to the expression ‘grace and truth,’ only a few explore this link more deeply. That this link exists and that it illumines the comparison between Moses and Jesus is – in view of the striking points of resemblance – hard to deny.
“On this assumption it is clear that in vs. 17 we are not dealing with a Pauline contrast between law and grace. In the giving of the law God revealed himself to Moses, when ‘Yahweh passed before him’ (Ex. 34:6) as the God of grace and truth, steadfast love, and faithfulness. But in that event Moses was not to see God’s glory, even though he had prayed for it (33:20). Only after God had passed by would he remove from Moses the hand that covered him (33:18f.).
“Therefore, the difference between Moses and Jesus Christ as it is described in Jn. 1:17 is not that Moses and the dispensation of which he was the great representative stood outside the grace and truth of which Jesus Christ was the personification. After all, it was just before the giving of the law that the Lord revealed himself to Moses in the ‘fullness’ of his grace. Still, however unequalled Moses’ significance was as the mediator between God and the people of Israel, he could not see God’s glory except from afar as the last rays of the sun, and even less could he be the bearer or dispenser of that glory in its fullness. But of Jesus Christ we are now told that grace and truth ‘came through him.’ That is, he not only proclaimed grace and truth but, as the one who was from above and into whose hand the Father had given all things (cf. 3:31, 35), he himself represented them in such a way that ‘from his fullness we have all been allowed to receive’ (vs. 16). It is in this totally different background of God’s revelation in Jesus Christ that everything ends in the last verse of the prologue, which is thus the summation and intensification of its entire content.”