Publisher Summary This chapter discusses modeling in general. This section examined the notion of a model in the light of the relationship between the craftsman and his work. It is a practical viewpoint and emphasizes that the enjoyment is in the practice of the craft or sullen art, not in the theorizing. Reprint P is the last of three dialogue papers, the others being App. 1, and App. 2. There is some overlap in matter, and the description of the logistical equation here is much fuller than it was in the first dialogue simply because much more was known about it in 1993 than had been in 1977. Reprint Q was written for John Villadsen's festschrift and grew out of a series of seminars on aesthetic considerations in science and engineering.