Linux and the Unix Philosophy
3.3 The Three Systems of Man
Man has the capacity to build only three systems. No matter how hard he may try, no matter how many hours, months, or years for which he may struggle, he eventually realizes that he is incapable of anything more. He simply cannot build a fourth. To believe otherwise is self-delusion.
Why only three? That is a tough question. One could speculate on several theories drawn from scientific, philosophical, and religious view-points. Each could offer a plausible explanation for why this occurs. But the simplest explanation may be that the design process of man's systems, like man himself, passes through three stages of life: youth, maturity, and old age.
In the youthful stage, people are full of vigor. They are the new kids on the block; they exude vitality, crave attention, and show lots of potential. As a person passes from youth to maturity, he or she becomes more useful to the world. Careers take shape. Long-term relationships develop. Influence widens in worldly affairs. The person makes an impact—good, bad, or otherwise. By the time old age sets in, the person has lost many abilities of youth. As physical prowess declines, much of the person's worldly influence fades as well. One's career becomes a memory. Resistance to change sets in. What remains is valuable wisdom based on experience.
Man's systems pass through these same stages in their development. Each system possesses characteristics that correlate with corresponding periods in life. All systems follow a path beginning at youth, transiting through maturity, and ending in old age.
Just as some men and women never reach old age, so some systems fail to mature as well. Often, this is due to external circumstances. Development plans may change. Funding for a project may be withdrawn. A potential customer may change his mind and decide to shop somewhere else. Any number of these factors could serve to prevent the system from reaching maturity. Under normal conditions, though, man carries the systems through all three stages. For our purposes we refer to these stages as the Three Systems of Man.
Most Unix developers don't know the Three Systems of Man by name, but they readily attest to their existence. Let's take a closer look at some of their characteristics.