Feste and Viola enjoy a some witty banter among intellectual equals in this scene. The Clown discovers that Viola can understand his riddling remarks better than anyone with whom he has previously encountered. Before this scene, Feste outwits everyone in his path, whether it be duke or peasant. People usually don't understand what he means when he talks, or they get frustrated and try to forget what he says. In this scene, however, Viola shows her intellectual abilities and her sense of humor by being able to play along with Feste. People who understand each other usually get along quite well. Here is what they both say about wit in that scene:
You have said, sir. To see this age! A sentence is but a
cheveril glove to a good wit: how quickly the wrong side
may be turned outward!
Nay, that's certain; they that dally nicely with words may
quickly make them wanton (III.i.10-14).
Here they both agree with one another about how the task of creating "good wit" is either a mastered art or a horrible embarrassment for a person engaged in such conversations. Truly, Viola and Feste are perfectly matched intellectually.