Here is a quote by Chesterton, which says what Annie Dillard was driving at in other quotes on this blog and also explains how she (and Cicero) could come to say some of the things I’ve quoted.
G.K. Chesterton, Chaucer
There is at the back of all our lives an abyss of light, more blinding and unfathomable than any abyss of darkness; and it is the abyss of actuality, of existence, of the fact that things truly are, and that we ourselves are incredibly and sometimes almost incredulously real. It is the fundamental fact of being, as against not being; it is unthinkable, yet we cannot unthink it, though we may sometimes be unthinking about it; unthinking and especially unthanking. For he who has realized this reality knows that it does outweigh, literally to infinity, all lesser regrets or arguments for negation, and that under all our grumblings there is a subconscious substance of gratitude. That light of the positive is the business of the poets, because they see all things in the light of it more than do other men [or they are able to give expression to what they see better than other men]. Chaucer was a child of light and not merely of twilight, the mere red twilight of one passing dawn of revolution, or the grey twilight of one dying day of social decline. He was the immediate heir of something like what Catholics call the Primitive Revelation; that glimpse that was given of the world when God saw that it was good; and so long as the artist gives us glimpses of that, it matters nothing that they are fragmentary or even trivial; whether it be in the mere fact that a medieval Court poet could appreciate a daisy, or that he could write in a sort of flash of blinding moonshine, of the lover who ‘slept no more than does the nightingale’. These things belong to the same world of wonder as the primary wonder at very existence of the world; higher than any common pros or cons, or likes and dislikes, however legitimate. Creation was the greatest of all Revolutions. It was for that, as the ancient poet said, that the morning stars sang together; and the most modern poets, like the medieval poets, may descend very far from that height of realization and stray and stumble and seem distraught; but we shall know them for the Sons of God, when they are still shouting for joy. This is something much more mystical and absolute than any modern thing that is called optimism; for it is only rarely that we realize like a vision filled with a chorus of giants, the primeval duty of Praise.