commonly used when describing an event, (usually bad), which has occurred and which could have been easily predict
ed if the warning sign
s had been heed
Example: "The writing was on the wall when Bob was moved from CEO to VP in charge of coffee-making - he was fired within three months".
The origin of the phrase is The Bible's story of King Belshazzar of Babylon and the drunken feast he held in 539 BC. According to the story, he used sacred vessels to serve wine at a celebration where the false gods of gold, silver, bronze and a few other lesser materials were worshipped. This displeased the spirit of his predecessor, King Nebuchadnezzar, who sent a disembodied hand which wrote a strange script on the wall in an unknown language. King Belshazzar consulted his wise men and courtiers but no one could interpet the writing. He offered an award to anyone who could decipher the writing, even going so far as declaring the person who could translate the writing would be his successor.
Daniel stepped forward and explained that the writing essentially said that 'your days are numbered'. That night King Belshazzar was slain.
I guess Belshazzar should've seen that coming.