The words feng shui in Chinese mean literally wind and water, though it's anyone's guess how wind and water link to the ancient custom of geomancy, which is what feng shui is.
Geomancy is the practice of arranging items in their best possible locations and positions.
Should this village go here or further down the road, over there? Should the buildings of the village face north or south or west or east? Should the gravesite for the villagers be nearer the hill or the river? Should the table be centered in the room or off to the side? Should the flowers in the pot lean left to capture incoming light or right to be shielded in the shade of the banyan tree?
In once sense feng shui is pure aesthetics, the art of putting objects in places most appealing to the eye. In another sense feng shui is pure pragmatics, putting things where they are most useful or nearby what is useful.
We might now hazard a guess as to the meanings of the words wind and water. Ancient artisans laid out villages and buildings with a view to their proximity to drinking water and with an understanding of prevailing winds that might either cool or freeze hut owners.
Feng shui might have begun in such practicalities six thousand years ago, but eventually it evolved into (or merged with) Chinese religious theories of aligning oneself with the power of chi by aligning everything in one's world with power of chi. Chi is the all-pervasive energy that envelops the universe. Harmony with chi brings health and happy relationships.
Feng shui thus shifted from being the prerogative of engineers and proto-home decorators to being the exclusive privilege of the Taoist and Neo-Confucian sacerdotal class, who turned feng shui into a ritual and a science at the same time, both of which gave it an air of mystique.
The priests devised special tools whereby they ascertained various forces at work in a given space, and after numerous calculations and incantations, they offered their advice.
A few late-twentieth-century well-heeled Westerners who had become overwhelmed by household clutter adopted feng shui. Some of them paid sizable sums of money to have their clutter rearranged in feng shui stylings.
One Californian I know had to have a new feng shui artist rearrange a former feng shui artist's work because the first one miscalculated due north.
This well illustrates how a religious custom may change over the centuries, beginning in practicality, morphing into high magic and spiritual necessity, and finally, in an utterly alien setting, transforming itself into an elite suburban conceit.