Imperative programmers, thou shalt not forget:
Edsger W. Dijkstra : first ALGOL 60 compiler (with Jaap Zonneveld), the THE operating system, correctness proofs, saving us from unstructured code,
Peter Naur: ALGOL 60 language definition
"Program testing can be used very effectively to show the _presence_ of bugs, but is hopelessly inadequate for showing their _absence_."
(an overhead slide by Dijkstra, quoted in The Dawn of Software Engineering, 2012)