The chaos that the Cat in the Hat brought to the narrator and Sally's lives comes to a pretty abrupt end. Just as quickly as he arrived and wreaked havoc, the Cat in the Hat cleans things up and leaves. And while he's at it, he totally dismisses all of the narrator and Sally's fears:

"So you see!" laughed the Cat,
"now your snow is all white!
Now your work is all done!
Now your house is all right!" (285-288)

Silly kids.

Looks like the Cat is making a point here: whatever the kids were so worried about wasn't actually such a big deal after all.