I have learned more from my failures than can ever be revealed in the cold print of a scientific article. [...] [Failures] are much more fun to hear … - Tony Hoare

[About Algol 60 subset implementation] [E]very occurrence of every subscript of every subscripted variable was on every occasion checked at run time against both the upper and the lower declared bounds of the array. Many years later we asked our customers whether they wished us to provide an option to switch off these checks in the interests of efficiency on production runs. Unanimously, they urged us not to - they already knew how frequently subscript errors occur on production runs where failure to detect them could be disastrous. I note with fear and horror that even in 1980, language designers and users have not learned this lesson. In any respectable branch of engineering, failure to observe such elementary precautions would have long been against the law.

Premature optimization is the root of all evil.

I have regarded it as the highest goal of programming language design to enable good ideas to be elegantly expressed.