Ruminations on the Number 4

There are four cardinal directions, four elements, four seasons (although here you could argue there are only two...),four suits in a deck of cards (regular or Tarot), four horsemen of the Apocalypse.

Carbon -- the base element of life on Earth -- has a valency of four. In biology, there are four nucleobase types in DNA: adenine, guanine, cytosine, and thymine.

Butterflies and dragonflies have four wings.

Most vehicles and furniture have four bases (wheels or legs).

In October 1904, the NYC Underground Subway system first opened.

However, in Chinese, Korean and Japanese cultures, four is considered unlucky because it sounds like the word "death".

Four is...

Balance;

A perfect family;

The number of bedrooms every house should have;

The only number in English for which the number of letters in its name is equal to the number itself;

The base number of plane (yes, I have no idea what that means);

My favorite number... and not for the obvious reason.