The phrase "a sobering lesson" is correct and usable in written English.
It can be used when referring to a realization or understanding that brings a sense of seriousness or gravity to a situation.
Example: "After the failure of the project, the team learned a sobering lesson about the importance of thorough planning."
Alternatives: "a harsh reality" or "a wake-up call".
I think it's a sobering lesson for Americans.
For many in the legal industry, Dewey's turmoil is a sobering lesson on unchecked ambitions.
The increased use of the word is the sign of a sobering lesson.
But doing this in the midst of a global recession was a sobering lesson in uncertainty.
Japanese firms' decade-long efforts to repay debt provide a sobering lesson.
Similarly, the tragedy of Tiananmen was a sobering lesson for would-be democratic revolutionaries.
It is a sobering lesson in listening to your supporters properly.
Chris was a very close friend of mine, and it was a very sobering lesson because there were a lot of young photographers there, and we kind of looked up to them, we admired them.
For Republican freshmen, however, the health care law offers a potentially sobering lesson about American democracy: after countless hours of drafting and floor debate, the health care bill Mr. Obama signed last year was the one written and approved by the Senate.
"Sparta" was the name of Conrad's base outside Haditha, but Robinson also offers a short, sobering lesson on the ancient model of the hyper-military in Greece, which adds depth to the more jolting history of the horrifying experiences of the modern military in Iraq.
For Republican freshmen, however, there was a potentially sobering lesson about American democracy to be learned from the health care law that they hate so much: after countless hours of drafting and floor debate, the health care bill that Mr. Obama signed last year was the one written and approved by the Senate.
