Stanley Fish, How Milton Works:

To those in whose breast it lodges, the holy is everywhere evident as the first principle of both seeing and doing. If you regard the world as God’s book before you ever take a particular look at it, any look you take will reveal, even as it generates, traces of his presence. If, on the other hand, the reality and omnipresence of God is not a basic premise of your consciousness, nothing you see will point to it and no amount of evidence will add up to it. You will miss it entirely, as Mammon [in Paradise Lost] does when all he can see in the soil and minerals of hell is material for a home-improvement project, one that will make up for the loss of heaven: “Nor want we skill or art, from whence to raise / Magnificence; and what can Heav’n show more?” He’s not kidding; he really means it. As far as he can see (a colloquialism I want to take very seriously), there is nothing more to see than the phenomena his art and skill will be able to produce; and those phenomena will bring heaven back to him because he never knew what it was in the first place…. Had he truly known heaven, he could not have moved away from it, for it would have been “a heaven within” (as it is for Abdiel, whose physical removal to the North leaves him unchanged in his essence); and were he now to know it by realizing what he had lost and could not replace by feats of construction, he would no longer have lost it, for its reality would be animating him even in exile and he would be in the position the Elder Brother imagines for his virtuous sister: “He that has light within his own clear breast / May sit i’th’ center, and enjoy bright day” (Comus, 381–382).