The Prime Minister has written a very significant article in this morning's Sunday Telegraph about our relationship with Europe.
He starts by rejecting two options that he believes would be wrong for our country.
First, accepting the status quo. He says more clearly that I have ever seen before that he is "not happy" with our current relationship. He argues that the EU costs too much, is too bureaucratic and meddles too much in issues that should be the responsibility of nation states, civic society or individuals and that whole swathes of legislation covering social issues, working time and home affairs should be scrapped.
Second, leaving the EU. He argues that unfettered access to European markets and, crucially, a say in how the rules of that market are written are vital for our country and that co-operating with our neighbours on foreign affairs maximises our influence in the world.
He goes on to point out that the euro crisis is changing Europe, forcing eurozone countries to integrate more and more closely, and that this offers us an opportunity but that we need to show "tactical and strategic patience".
He ends by opening the door to a referendum on any revised relationship.
I know some will react with cynicism - they'll say he promised a referendum on Lisbon and didn't deliver one (actually, he promised a referendum if Lisbon hadn't been ratified by the time he became Prime Minister but that's not what most people heard) - but I think this is hugely significant.
The question of our relationship with Europe has dogged British politics for years. Anyone under the age of 55 didn't get to vote in the 1975 referendum and many of those who did feel that the EU is a very different creature from the Common Market that they voted to join. Holding a referendum is the only way to settle the issue - and the Prime Minister is right to say that the sensible time to hold that referendum is when the options before us are clear.