Having searched for a loving, omniscient God in the first half of the book and questioned a cruel, careless one in the second, Dillard finds a way to reconcile them. She returns to the cat from the first sentence of the book, even reusing the first half of that sentence:
I used to have a cat, an old fighting tom, who sprang through the open window by my bed and pummeled my chest, barely sheathing his claws. (15.28)
The cat, like the world, has brutalized her. She's seen some seriously messed-up stuff at Tinker Creek, including a lot of wounded and scarred animals, and she acknowledges that she's wounded and scarred as well. This is Annie Dillard, so obviously she's going to end her book by quoting somebody—it's kind of been her thing throughout—and in this case, Ralph Waldo Emerson's her man:
"I dreamed […] that I saw this world […] diminished to the size of an apple. Then an angel took it in his hand and brought it to me and said, 'This must thou eat.' And I ate the world." (15.29)
Eating the world, she thinks, is a pretty good idea, and you might as well be thankful for it, even if it's a little bruised and wormy. And hey, here's someone else who ate the world: that creepy, frog-sucking water bug. She cites the somewhat manic English preacher Billy Bray, who was known for dancing and singing during his sermons, and says that as she continues to explore the world, she is, like Bray, "exultant, in a daze, dancing" (15.29). Given all the destruction she's observed, there are way worse places to land.
Now that you've made it through, go have some apple pie or apple cider or Apple Jacks or something. (Don't forget to drink the sugary, orange milk—preferably through a straw, like a giant water bug.)