SOURCE: Gaar, Alice Carol. “The Human as Machine Analog: The Big Daddy of Interchangeable Parts in the Fiction of Robert A. Heinlein.” In Robert A. Heinlein, edited by Joseph D. Olander and Martin Harry Greenberg, pp. 64-82. New York: Taplinger Publishing Co., 1978.

In the following essay, Gaar explores the theme of interchangeable parts and the central figure in several of Heinlein's novellas and short stories.

There is a discontinuity between the rate of moral development in the human being and the exponential rate of technological progress. One might state it in a simpler way: The tool grows better and better, while its user is the same old hairless ape. The hairless ape can fly, but emotionally and morally he is still crawling. The machine works very well; maybe we don't work at all. Are the machines getting out of control, or were we never under control?

Robert A...