Why are things called 东四 dòng xi (east west)?

I have been using the Decipher Chinese app everyday since I found out about it and I'm happy with it even though I have not paid to subscribe, which I don't think I will. 

This is because I'm quite invested in using Anki and I don't need another SRS app to complicate my learning of the language. What I need to do now is to figure Anki out a bit on its technical side and use it more effectively. 

For example, now I can add words and phrases from Decipher to Anki and reposition it to appear first without having to wait until I reach the 6000th card!

Decipher does have some interesting articles, like this one. I wondered before why are "things" in Chinese called 东四 dòng xi or literally east west, and not 南北 nán běi or south north. 

It is because of the Chinese 五行 wǔ xíng, which is the five phases of Chinese philosophy vis-à-vis wood, fire, earth, metal and water, the five elements that are believed to represent everything on earth. 

And these elements are represented by the directions: east being wood, south fire, west metal and north water. 

And because the only two items that can be held are wood and metal, things are therefore represented by east and west, hence 东四 dòng xi. 

pearlie