“Systems with unknown behavioral properties require the implementation of iterations which are intrinsic to the design process but which are normally hidden from view. Certainly when a solution to a well-understood problem is synthesized, weak designs are mentally rejected by a competent designer in a matter of moments. On larger or more complicated efforts, alternative designs must be explicitly and iteratively implemented. The designers perhaps out of vanity, often are at pains to hide the many versions which were abandoned and if absolute failure occurs, of course one hears nothing. Thus the topic of design iteration is rarely discussed. Perhaps we should not be surprised to see this phenomenon with software, for it is a rare author indeed who publicizes the amount of editing or the number of drafts he took to produce a manuscript.”

"A Managerial View of the Multics System Development" http://www.multicians.org/managerial.html, Conference on Research Directions in Software Technology, Providence, Rhode Island, October 10-12, 1977 published in Research Directions in Software Technology (1978), P. Wegner (ed.), MIT Press, ISBN 0262230968, pp. 139-158. Also reprinted in Tutorial: Software Management, Donald J. Reifer (ed.), IEEE Computer Society Press, (1979, 1981, 1986)