Honest to God, I think Kent Beck's contribution to all this has been taking stuff that he and I discovered quietly together, or picked up from other programmers, and taking it to the limit. Taking it to the limit. And the fact that it actually holds up — and a lot of it improves — when taking it to the limit is why it should naturally be called "Extreme." Kent's single biggest contribution is being daring enough to say, "This is all that matters, and we should do it all the time."

A Conversation with Ward Cunningham (2003) - To Plan or Not To Plan