Third Isaiah, intertextutality, and history

In my post The Biblical canon and Biblical referentiality, I stated that, as far as Childs is concerned, the final form of the canon of Scripture is not a totally hermeneutically sealed unit, such that one can make sense of the parts without reference to extra-textual realities. He certainly credits the final form of the text with far more integrity than many of his colleagues, but nevertheless the meaning of this final form is contoured to a large degree by the particular manner in which it came to existence. This calls for a subtle form of exegesis, one which takes into account the different "levels of consciousness" present within the "final form."
"First, Third Isaiah remains a prophetic collection, both in form and content, which means there is an encounter with actual historical realities, albeit seen in the light of the divine. This dimension dare not be flattened simply into a type of learned scribal activity dealing exclusively with literary texts. Second, not every occurrence of a parallel [with Second or First Isaiah] can be assigned to an intentional reuse. A critical assessment must be made that reckons with the theological substance at stake beyond merely identifying formal parallelism discovered by the perusal of a concordance.1"

Childs' reference to the "theological substance" of the text here highlights another dimension of his concern to respect the historical nature of the text. Christianity claims that the Old Testament is a witness to a divine reality that was ultimately revealed in Christ. This was the concern of allegorical exegesis. Historical Criticism rightly retains this sense of extra-textual referentiality. Rejecting the constraints of the historical dimension and treating the text as a space for free-floating signifiers risks dampening its ability to point beyond itself the the reality that undergirds both past, present, and future.

1Childs, Isaiah, 462. S