[P]rogramming properly should be regarded as an activity by which the programmers form or achieve a certain kind of insight, a theory, of the matters at hand. This suggestion is in contrast to what appears to be a more common notion, that programming should be regarded as a production of a program and certain other texts.This insight has ramifications for the anthropology and life-cycle of large projects, where in order to produce modifications to an existing program without compromising the structure the programmers must understand the underlying theory. Since such an understanding is not easily acquired, we have Fred Brooks' observation that adding more manpower to a late project makes it later as a corollary: The people who understand the theory have to induct the newcomers, thus soaking up both groups' productivity.
Having had the experience myself of being brought late onto an existing project, I can appreciate first-hand how hard "learning the theory" can be. At other times I have developed sophisticated algorithms that I don't think anyone else who came after was game to touch!
Understanding and acknowledging this element of software development should be helpful in managing large-scale and long-term developments. Of course, since it accepts the human side of programming, no simple "solutions" follow, but its implications for quality assurance, recruiting, and -- as Naur points out -- the status of programming as a profession, are far-reaching.