The remark from Alan Perlis feels pretty accurate to me: You think you know when you can learn, are more sure when you can write, even more when you can teach,

The remark from Alan Perlis feels pretty accurate to me: You think you know when you can learn, are more sure when you can write, even more when you can teach, but certain when you can program. I can read a book on a subject, and understand it to a degree. If I write down what I learned in my own words, then I must come to grips with the fact that I didn't understand everything; writing it down forces me to come to a better, more organized understanding. Teaching it to someone else means I must be able to explain for someone who does not necessarily have my own background, and who may stop me to ask questions. Programming the knowledge to a computer means that I must account for all questions; the knowledge must be completely and precisely defined. I reckon very little knowledge has yet been adequately programmed into a computer, but many people stop at the first step, and never write or teach.