When we made a difficult decision from where there is no way back, we say we cross the Rubicon. Basically crossing the Rubicon means the point of no return.
This high-level idiom comes from an event in ancient Roman history. In 49 BC Julius Caesar's army crossed the Rubicon River, an action that started civil. It was forbidden for any army to cross the border river, so when Caesar's army did, he knew he was doing something which would have important results that could not be changed later.
This idiom appeared yesterday in a headline of a British newspaper article, "David Cameron refuses to 'cross Rubicon' and write press law".
The article quotes British Prime Minister, David Cameron, who said he was not willing to cross the Rubicon by giving the government the power to control the activity of newspapers. He said, "For the first time we would have crossed the Rubicon of writing elements of press regulation into the law of the land. We should, I believe, be wary of any legislation that has the potential to infringe free speech and a free press."
"She crossed the Rubicon when she got that huge tattoo on her back!"
"Many European countries have crossed the Rubicon and taken the euro as their currency."
Do you use this idiom in your language or something similar? Can you think of any other modern examples of when someone crossed the Rubicon.