The Best Theory Is Inspired By Practice.

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.

An Algorithm Must Be Seen To Be Believed.

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.

... The Designer Of A New System Must Not Only Be The Implementor And The First Large-scale User; The Designer Should Also Write The First User Manual. ... If I Had Not Participated Fully In All These Activities, Literally Hundreds Of Improvements Would Never Have Been Made, Because I Would Never Have Thought Of Them Or Perceived Why They Were Important.

The Best Theory Is Inspired By Practice.