I find this fascinating and thought provoking. I read it as essentially saying "teach your students how to make mistakes". Which is interesting because isn't that why we practice things...to "not make mistakes"? But I think this can be a powerful strategy. If we teach students "how to make mistakes" (or what ones will be the most beneficial) they won't be scared of the inevitable, and be confident in their ability to grow from them, and see them as essential in the learning process.