The writing on the wall is a portent predicating the end of civilization, of a type of behavior, or of any large company or human organization. The phrase is usually used in a negative way to suggest that the end is near. Its roots are in the bible, and a modern, somewhat literal interpretation might be an individual who wears a signboard that specifically states that “The end is near.” While this the writing on a signboard, rather than a wall, it is still a means by which people try to convince others that civilization is rapidly coming to an end.
The Book of Daniel in the Old Testament contains the first known reference to the writing on the wall. In Daniel 5:1-31, Belshazzar, the King of Babylon, holds a drunken feast where he displays holy items stolen from the Temple in Jerusalem. When the King and his subjects hold the items, writing begins to appear on the wall, and Daniel is brought in to interpret the words, which seem to have little meaning. Daniel warns the King that his days are numbered, and his kingdom will soon be destroyed.
Daniel’s interpretation is, of course, correct. King Belshazzar is killed that same night and the country is sent into disorder as Darius of the Medes takes over the kingship. As Daniel predicts, the kingdom is split between the Medes and the Persians, and signifies the end of Babylonian supremacy.
The specific writing on the wall in Daniel are the following words: Mene, Tekel, and Parsin. Mene translates as toll, the price the Babylonians will pay; Tekel means weight, or judgment; and Parsin means division, and is also a corruption of the word Persians, the race that will claim part of the Babylonian kingdom.
In modern usage, people often use the phase to suggest that they know something is coming to and end, prompting action. For example, someone could say that “She knew she had to get a new job immediately. She saw the writing on the wall and didn’t want to wait until the company started its downsizing efforts.”