In a car engine the piston cannot do the crankshaft job. The crankshaft cannot do the connecting rod job. A spark plug only does one thing and the same can be said about the rest of the parts.
Computer software is more flexible, even so the Unix base system uses a similar policy (sometimes referred to as KISS, acronym for “Keep it simple, stupid”): it provides a group of small programs whose slogan is each one “do just one thing and do it well”, plus a way to combine them, by a process called “piping,” which allows you to perform more complex tasks.
More than two decades ago, when I was studying violoncello at the music conservatory of my country, Argentina, I enrolled in a luthier course that an old man was giving on Saturdays. In case you don't know, a luthier is the one who makes musical instruments, especially those of strings you see in orchestras. Some people get surprised when they are told that to make a violin front plate, or “belly”, the luthier starts from a square block of solid wood and obtains the concavity by manually carving with gouges. Along this process, with the help of a caliper, he controls to preserve the same thickness throughout the belly. A very difficult task indeed and, in case you're wondering, yes: the cello belly is made in the same way. Both jobs, playing musical instruments and constructing them, demand full commitment, I had to decide; not without regretting I had to abandon this course after a month. This experience was also illustrative of another important aspect. I remember a brief dialog I had with the professor before leaving the course in which he told me that he had lived in the United States for several years, and that he had a job there, in a piano factory, with an excellent salary. When I asked him the obvious, why he returned to Argentina to earn less than a seventh of the money he earned in the United States, he replied that he had grown bored of cutting stupid piano keys all day long. There, he was just one more piece in a factory assembly line.
Modern society is like a machine. It requires each person to perform a specific task, like the tools in the Unix example. All day, everyday and, with “luck,” throughout life. Of course this is economically productive but what's good for machines is not necessarly good for people. As time passes, people increasingly resemble pistons or spark plugs, losing the quality that distinguishes them as living organisms: their ability to adapt or even to see the context.