The ins and outs of idioms come from which of the following activities?

Context, originally a feng shui superstition, refers to the source and destination of mountains; Now refers to a clue to the ins and outs of a thing. Our ancestors began to worship dragons very early. The legendary dragon is a monster that stretches like a mountain, so people often compare mountains to dragons.

The way to choose geomantic omen is summarized as dragon, cave, sand and water, and its principles are dragon truth, cave, sand circle and water embrace. Dragon refers to the mountain, and dragon really refers to the mountain where life flows. Among them, the main mountain is "Lailong"; The ridge winding down from the top of the mountain is called "Long Mai", also called "pulse removal".

Context explanation:

Dragon used to refer to people who were superstitious about Feng Shui, and compared the rolling landscape to "dragon". The leading place is called "Dragon and Dragon". If you are located in Dragon and Dragon, you will be lucky, smooth and prosperous. The terrain from the dragon's head to the dragon's tail, like a vein, is called "vein", which is a metaphor for the origin of people or things or the cause and effect of things.

Example: Wu Ming Rachel's "The Study of Cattle Face in Ji Zun": "There are thousands of fertile fields here, and it is suffocating everywhere." Chapter 2 of Yang Mo's Song of Youth: "But what does he do? What is his story? She couldn't help but be curious and always wanted to ask. "