First, it comes from spoken language.
This idiom is widely circulated in people's spoken language, and then seen in the text, which is generally popular and vivid. Such as: cheerful, mobile, changeable, pointing, tailored, beating around the bush, completely clean and so on.
Second, it originated from ancient books.
That is, from thousands of years of ancient books, it can be divided into:
① Generalization of ancient fables, such as: self-contradiction, foolish old man moving mountains, waiting for rabbits, gilding the lily, imitating the tiger but not the tiger, worrying too much, etc.
(2) Summary of historical stories, such as: trees and grass are all soldiers, eager for plums to quench their thirst, cross the rubicon, return to Zhao intact, humble salary, and care for the thatched cottage.
(3) Excerpts or excerpts from famous sayings and aphorisms in ancient books, such as: never tire of learning, never tire of teaching, suddenly enlightened, everything goes to the root of the matter, everything goes smoothly, people are harmonious, relaxed and happy, and make great efforts to govern.
Third, it comes from foreign words.
For example, idioms translated or rewritten according to Buddhist scriptures: a flash in the pan, falling to the ground, gathering sand into a tower, returning to the light, being alone, showing up and so on. Another example is an idiom from French: take a ticket from the fire, ivory tower, etc.
Fourth, the newly created.
With the development of society, idioms are constantly emerging and evolving. From the works of famous artists and the spoken language of the masses, some new idioms are constantly emerging. Such as: save as fast as possible, strive for the upper reaches, innovate, race against time, cherish the present and cherish the past, be self-reliant, let a hundred flowers blossom, make the past serve the present, and so on.