Designer, implementor, user, writer A Fragment by Donald Knuth dl.acm.org Thus, I came to the conclusion that 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. The separation of any of these four components would have hurt TeX significantly. 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. Eating your own dog food making
The evolution of devices All the first antecedents of man's devices were given him by Nature. Every one of his devices is traceable back to something in nature which suggested the first remote and primitive beginnings of its evolution. And every feature in art that man's mind conceived is conceived by a mind that has evolved as a part of nature: that grew out of nature. The evolution of devices is as much a natural process as the evolution of organisms. David Pye, The Nature and Aesthetics of Design The Evolution of Useful Things creativity