Donald Knuth

What they built

Author of The Art of Computer Programming (1968–, still in progress), the foundational multi-volume work on algorithms. Designed and implemented TeX (1978) and METAFONT to typeset mathematics to his own standards. Developed literate programming and the WEB/CWEB systems. Invented attribute grammars, LR(k) parsing analysis, and the Knuth-Morris-Pratt string-search algorithm. Turing Award 1974. Emeritus at Stanford since 1992.

In their own words

• "Programmers waste enormous amounts of time thinking about, or worrying about, the speed of noncritical parts of their programs… We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil. Yet we should not pass up our opportunities in that critical 3%." — Structured Programming with go to Statements, ACM Computing Surveys, 1974. The full passage is an argument for careful goto use in the critical 3%, not a blanket anti-optimization slogan.
• "Science is what we understand well enough to explain to a computer. Art is everything else." — foreword to A=B (Petkovšek, Wilf, Zeilberger, 1996).
• "I can't go to a restaurant and order food because I keep looking at the fonts on the menu." — interview, 2008, on what designing TeX and METAFONT did to him.
• "Email is a wonderful thing for people whose role in life is to be on top of things. But not for me; my role is to be on the bottom of things." — knuth.html FAQ. He stopped using email in 1990 and has his secretary print incoming mail for him to respond to on paper.
• On why he writes in WEB: literate programming "changes the programmer's attitude. You strive for something that's artistically acceptable, not just functional." — various interviews.

Principles as they articulated them

• Programs should be written for humans first, then for machines (literate programming).
• Typography is part of communication; mathematics deserves the same care as serif lead.
• Correct the critical 3%; leave the other 97% alone.
• Depth over breadth; finish a volume, even if it takes 40 years.
• Stay off the communication treadmill. Batch responses. Don't be reachable.

What surprised me in research

• Knuth's famous $2.56 "error finder" checks are no longer real checks. He stopped issuing negotiable checks in October 2008 after widespread check-fraud attempts; since then finders get a "hexadecimal certificate" drawn on the fictional Bank of San Serriffe. A collector's item, not spendable money.
• The Art of Computer Programming is genuinely still being written. Volume 4B shipped late 2022; the first ~275 pages of Volume 4C appeared in print, with Fascicle 7 ("Constraint Satisfaction") published February 5, 2025. He is in his late 80s and still publishing errata to 4B (most recent update on the Stanford page logged April 9, 2026).
• Knuth's real feeling about the "premature optimization" quote is that it has been used to justify exactly the sloppiness he was writing against. Multiple secondary sources note that "the people who most often quote it would be horrified by its original context" — the paper defends goto for inner-loop performance work.
• He works in 3D: for a decade he has been writing TAOCP on a standing desk and uses pencil and paper heavily before any code.

Recent or later work

Continues sole authorship of TAOCP into Volume 4C and planned Volume 5. Semi-annual "Christmas Lectures" at Stanford on topics ranging from the Dancing Links algorithm to tricks from Volume 4. No interviews on Twitter/podcasts beyond the Lex Fridman conversations (2019, 2021). He accepts speaking invitations selectively; the pace of his public presence is deliberately slow.

Sources

• https://www-cs-faculty.stanford.edu/~knuth/news.html — Knuth: Recent News — stanford.edu
• https://www-cs-faculty.stanford.edu/~knuth/faq.html — Knuth: FAQ (email policy, checks) — stanford.edu
• https://en.wikipedia.org/wiki/Knuth_reward_check — Knuth reward check — wikipedia.org
• https://lexfridman.com/donald-knuth-2/ — Lex Fridman Podcast #219: Donald Knuth — lexfridman.com
• https://ubiquity.acm.org/article.cfm?id=1513451 — The Fallacy of Premature Optimization — ubiquity.acm.org