The speaker will discuss what he considers to be the most important outcome of his work developing TeX in the 1980s, namely the accidental discovery of a new approach to programming --- which caused a radical change in his own coding style. Ever since then, he has aimed to write programs for human beings (not computers) to read. The result is that the programs have fewer mistakes, they are easier to modify and maintain, and they can indeed be understood by human beings. This facilitates reproducible research, among other things.