In the early 1990s I gave presentations on using graphics in software development, several times with Alan Kay in the audience. At one point, I believe to remember, he mentioned he hadn’t seen that kind of vision or clarity since Sutherland‘s Sketchpad. Two decades later I downloaded Sutherland’s 1963 thesis, and read some of it.
Recently I searched Sutherland’s Sketchpad thesis for the word “constraint” and found it 127 times in 143 pages.
To quote verbatim from Chapter I, Introduction: