Theoretical change is itself driven by a feedback mechanism, as we noted in chapter 3: science learns from failure. But when a theory fails, like say when the Unilever mathematicians failed in their attempt to create an efficient nozzle design, it takes time to come up with a new, all-encompassing theory. To gain practical knowledge, however, you just need to try a different-sized aperture. Tinkering, tweaking, learning from practical mistakes: all have speed on their side. Theoretical leaps, while prodigious, are far less frequent.
