The Best Theory Is Inspired By Practice.

I Remember That Mathematicians Were Telling Me In The 1960s That They Would Recognize Computer Science As A Mature Discipline When It Had 1,000 Deep Algorithms. I Think We've Probably Reached 500.

...one Of The Most Important Lessons, Perhaps, Is The Fact That Software Is Hard. From Now On I Shall Have Significantly Greater Respect For Every Successful Software Tool That I Encounter. During The Past Decade I Was Surprised To Learn That The Writing Of Programs For Tex And Metafont Proved To Be Much More Difficult Than All The Other Things I Had Done (like Proving Theorems Or Writing Books). The Creation Of Good Software Demand A Significiantly Higher Standard Of Accuracy Than Those Other Things Do, And It Requires A Longer Attention Span Than Other Intellectual Tasks.

The Most Important Thing In The Programming Language Is The Name. A Language Will Not Succeed Without A Good Name. I Have Recently Invented A Very Good Name And Now I Am Looking For A Suitable Language.

When Certain Concepts Of Tex Are Introduced Informally, General Rules Will Be Stated; Afterwards You Will Find That The Rules Aren't Strictly True. In General, The Later Chapters Contain More Reliable Information Than The Earlier Ones Do. The Author Feels That This Technique Of Deliberate Lying Will Actually Make It Easier For You To Learn The Ideas. Once You Understand A Simple But False Rule, It Will Not Be Hard To Supplement That Rule With Its Exceptions.

Programmers Waste Enormous Amounts Of Time Thinking About, Or Worrying About, The Speed Of Noncritical Parts Of Their Programs, And These Attempts At Efficiency Actually Have A Strong Negative Impact When Debugging And Maintenance Are Considered. 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%.