The continued adaptation, modification and correction of errors in them, is essentially dependent on a certain kind of knowledge possessed by a group of programmers

(written by lawrence krubner, however indented passages are often quotes). You can contact lawrence at: lawrence@krubner.com

Interesting:

The conclusion seems inescapable that with at least certain kinds of large programs, the continued adaptation, modification and correction of errors in them, is essentially dependent on a certain kind of knowledge possessed by a group of programmers who are closely and continuously connected with them.

Source