3 Is Elegant

A thing is elegant when it in addition of doing its duty effectively and efficiently also do it seemlessly i.e. it not looks like any effort is being put in though ofcourse a lot of effort is being put in.

Looking at something which is trying hard to hit its target (effectiveness) or trying hard to hit target spending minimum resources (efficiency) is hard on nerves. Its same as seeing thick pillars supporting a roof. The pillars are obviously trying hard. Its also same as seeing a complex pattern of arches supporting a roof. The arches though use minimum resources are still obviously trying hard.

The whole point of elegance is minimum visibility of effort. Supporting of roof is hard work and therefore do require trying hard but that effort can be made less visible for example by using better material in pillars thereby reducing thickness of pillars, increasing number of arches thereby reducing the complexity of the pattern of arches, making roof in shape of a dome thereby hiding the complexity of the pattern of bricks behind plaster etc.

Watching performance of an experienced artist, on the contrary, is an enjoyment because of the smooth flow. The performer himself enjoy giving performance.

Elegance in arts come only with practise. Its impossible for humans to be elegant in doing something they are doing the first time.

How is 3 elegant? Why only 3 is elegant?

You want anything that you use and depend on to be more than 1. 1 is sufficient for the need at hand but for future needs its wise to have some spare ones available because the thing may become unusable or unavailable. 2 covers most of these issues but not sufficiently so. Its good to have backups and alternatives but life is big enough to have even those fail frequently enough.

Like in computer programming every inherently solvable problem can be solved just by adding another layer of indirection, in real life every inherently solvable problem can be solved by adding another layer of covering. Therefore, keeping backups of backups reduce the frequency of issues to one in decades level, beyond that, by the way, is impossible for humans to flawlessly support therefore such problems are inherently insolvable.

Covering as much cases as can be humanly covered is effectiveness which is one of the three requirements of elegance. The other two are efficiency and seamlessness.

The only way to achieve efficiency is by increasing complexity. Overall resource consumption get reduced but mental effort get increased. The mental effort get increased because a system must be made and maintained. Maintenance means that some of the efforts are moved to future. Still the sum of all of the efforts including the mental effort over all of the times is less than the effort that was required before the increase in efficiency.

Efficiency always come by increasing the number of constituent parts i.e. by decreasing the size of each part. This has a cost associated with it. Its the cost of management of interactions between parts. More parts there are, more interactions between them. Very soon the system become too complex to be humanly manageable. We have to find a sweet spot.

Perhaps for small systems, 3 is the sweet spot number of parts. Its enough for backups of backups and still efficient because of manageable interactions between parts aka complexity. For large systems it really depends on what the system is trying to achieve. By small systems I mean maids in house, backups of data, exit-ways from a room, height of rooms for given heights of people using the room, widths of corridors and roads, light sources in room, drives in hard disk, types of disks supported by computer system, pairs of shoes of a person, types of entertainment near one's house, types of means of transportation, sea-ports in a country, cushions to absorb shocks etc.