This is one of my favourite stories about how to get really good at something. I frequently say it to myself when I discover I have thrown myself in at the deep end of a technical problem :-)
My second blog post last spring (http://williambswift.blogspot.com/2009/03/value-of-mistakes-...) was about the value of making mistakes for learning. I see I missed the "making mistakes on purpose" bit, and am going to add a new post now about that. The general idea was referred to several times in older Whole Earth Catalogs, I should have remembered it earlier.