The result of the author's extensive practical experience: a decade in computer process control using large scale systems, another decade in machine pattern-recognition for vision systems, and nearly a decade dealing with artificial intelligence and expert systems. These real-life projects have taught V mos a critical appreciation of, and respect for, both abstract theory and the practical methodology that grows out of--and, in turn, shapes--those theories.Machine representation means a level of formalization that can be expressed by the instruments of mathematics, whereas programming is not more and not less than a special linguistic translation of these mathematical formulae. How these all are related and controlled is a most practical philosophical and computation professional task. Wide experience in the practical fields of computer science, and the research of the underlying theoretical issues have led V mos to the development of the attitude and activity of constructive skepticism.