The job of formal methods is to elucidate the assumptions upon which formal correctness depends.

Premature optimization is the root of all evil in programming.

I couldn't resist the temptation to put in a null reference, simply because it was so easy to implement. This has led to innumerable errors, vulnerabilities, and system crashes, which have probably caused a billion dollars of pain and damage in the last forty years.

I call it my billion-dollar mistake. It was the invention of the null reference in 1965.

The price of reliability is the pursuit of the utmost simplicity. It is a price which the very rich may find hard to pay.

In the development of the understanding of complex phenomena, the most powerful tool available to the human intellect is abstraction. Abstraction arises from the recognition of similarities between certain objects, situations, or processes in the real world and the decision to concentrate on these similarities and to ignore, for the time being, their differences.

An ultimate joint challenge for the biological and the computational sciences is the understanding of the mechanisms of the human brain, and its relationship with the human mind.