Program testing can be used to show the presence of bugs, but never to show their absence! -- EWD249

There are two ways of constructing a software design: One way is to make it so simple that there are obviously no deficiencies, and the other way is to make it so complicated that there are no obvious deficiencies. The first method is far more difficult. It demands the same skill, devotion, insight, and even inspiration as the discovery of the simple physical laws which underlie the complex phenomena of nature. -- Tony Hoare

A convincing demonstration of correctness being impossible as long as the mechanism is regarded as a black box, our only hope lies in not regarding the mechanism as a black box -- Edsgar W. Dijkstra

In fact, my main conclusion after spending ten years of my life working on the TEX project is that software is hard. It’s harder than anything else I’ve ever had to do. -- Donald Knuth

Thinking doesn't guarantee that we won't make mistakes. But not thinking guarantees that we will. -- Leslie Lamport

A good technical writer, trying not to be obvious about it, but says everything twice: formally and informally. Or maybe three times. -- Don Knuth

For critical modules, like the kernel and error correction routines, we walked through the compiled assembly code. We took the time to simulate the step-by-step operation of the machine code using pen and paper, each team member role-playing parts of the microprocessor (Phil would pretend to be the accumulator, Lou the program counter, me the index register). By the end of it all, we had several people who knew the defib's software like the back of their hand. And we had demonstrably the most reliable real time software ever written. After amassing several thousand implant-years, we measured a bug rate of less than one in 10,000 lines - Stephen Wilson

You never know how things are, you just know how things where -- Joe Armstrong on networked system
(Phils corollary: people think doing things in the middle (aka the master) versus doing things at the edge (aka the slaves) makes sense but they seem to ignore physics, e.g. what happens when you have lost communications)

"Who is to say which of us, should envy the other" -- George V to Sir Ernest

"Be nothing, and you will have everything to give to others." – Master Po

See also:

  1. EDS Quotes