Unveiling the character of the law

On Friday I had an interesting discussion with a friend about the character of the Old Testament law and the extent to which it was "written in stone" as opposed to having a more dynamic character because it was "veiled" and required contemplation and investigation. I vaguely recalled Karl Barth's view of Revelation and the veiled-unveiled dialectic he emphasized.
I think the passage below may be one of the (many?) relevant ones, but welcome alternative suggestions. 

Revelation in the Bible means the self-unveiling, imparted to men, of the God who by nature cannot be unveiled to men. The element of self-unveiling in this definition may be described as the historical if not the logical or material centre of the biblical revelation. When the Bible speaks of revelation, it does so in the form of the record of a history or a series of histories. The content of this history or of each of these histories, however, is that self-unveiling of God. But as the record is given, our experience also is, of course, that the One who thus unveils Himself is the God who by nature cannot be unveiled to men, and that this self-unveiling is to specific men. Logically and materially this is just as important as the recorded self-unveiling. Historically the latter constitutes the centre....., self-unveiling means that God does what men themselves cannot do in any sense or in any way: He makes Himself present, known and significant to them as God. In the historical life of men He takes up a place, and a very specific place at that, and makes Himself the object of human contemplation, human experience, human thought and human speech. 

Karl Barth, Church Dogmatics I.1 The Doctrine of the Word of God, p. 315.

Moses with tablets of the Ten Commandments, Rembrandt (1659)