A collision awaits President Donald Trump. Exactly when it will take place isn't clear, but it is almost certain to occur. The extravagance of the president's rhetoric is soon to meet the reality of governing.
The president's inaugural address was perhaps the baldest example of the rhetorical bravado that marked his time as a New York developer, a reality TV star and, yes, as a candidate. Restraint is not in his vocabulary.
Mr Trump's inaugural address has drawn considerable criticism for its overall tone, for the dark portrait he drew of the state of the country, for its inward and insular vision, and for the general absence of typical inaugural themes of unity and American exceptionalism.
Those are all valid critiques of this most unusual of American inaugural addresses. But set them aside for the moment and take the address as a genuine expression of Mr Trump's vision and ambitions as president. He will soon be measured against the promises he's made, and he opened his presidency by setting an incredibly high bar for himself. Making good won't be easy.
The opposition will come from many directions. The millions of people who took to the streets in cities around the country and around the world on Saturday speak to the resistance he will face as president. He will be opposed both for what he stands for and for who he is. Beyond that, he will have to prove he can translate the skills of a businessman to the messier process of legislating and presidential decision-making. The slow process of populating his new government should raise cautions.
His inaugural speech was a call to arms, a renewed effort to summon the anger that exists in parts of the population against the economic and cultural elites. Rather than an address to bring the country together, it was an expression of the divisions he successfully exploited as a candidate.
As in the campaign, it was a pitch-perfect rendering of the frustrations that have fuelled his rise with a message of nationalism, populism and dismissal of his critics. That alone won't suffice now that he is president. He will be expected to deliver on the promise of a fundamental shift in governing priorities.
What would he do as president? Here are just a few actions, based on his Friday speech. He would build more roads and highways and bridges and tunnels and airports than any president in recent memory. He would bring back the millions of jobs that have moved overseas and/or prevent the continuation of that flow.
He would reverse globalism in some form or fashion. He would seek to ensure products sold in America are made in America. He would set up new barriers to protect the country, whether a physical wall to impede illegal immigration or financial impediments in the form of tariffs or border fees. And he would do all that now. As he put it: "The American carnage stops right here and stops right now."
Mr Trump can rail against the political establishment all he wants. It worked for him as a candidate, and he appears to believe it will work for him as president. Some of the first words out of his mouth as the 45th president were used to denigrate the sea of political humanity sitting behind him on the Capitol's West Front. He was in no mood to offer olive branches or promises of co-operation, whether to his presidential predecessors or the leaders of Congress.
It wasn't just one poke in the eye but a series of broadsides against the established order as he charged those in attendance with being guilty of lining their own pockets at the expense of the people.
"That all changes, starting right here and right now," he said, "because this moment is your moment. It belongs to you."
There are, however, enough contradictions within Mr Trump's presidency and administration to call into question what he had to say in that speech. Strong and forceful rhetoric on the part of leaders can be valuable in rallying a nation in the face of adversity; Mr Trump apparently believes this is one of those moments. But over-promising and not delivering would leave him vulnerable to the charge that he is what he criticised: all talk and no action.
By all indications, the inaugural address represented a fusion of the ideas and visions of Mr Trump, chief strategist Stephen Bannon and senior policy adviser Stephen Miller. But there's little to indicate that such a view of the world is shared widely in the new administration or whether it represents fully all of Mr Trump's views.
White House chief of staff Reince Priebus has never been known for holding views like that. How much will he and other allies who are part of Mr Trump's White House team seek to temper the anti-globalist vision? However clearly Mr Trump spoke on Friday, turning those words into governing principles and then into presidential actions or legislative recommendations is likely to be a cumbersome and at times combative process.
Outside the White House, Mr Trump faces potential pushback from members of his own cabinet. Just one example is Defence Secretary James Mattis, who has a more positive view of Nato than does the president, as well as a much more sceptical view of Russia.
It's also important to remember that Mr Trump is the first president in history with neither experience in government nor service in the military. He's been a developer and a dealmaker and has a high opinion of his negotiating skills, perhaps for good reason. But he's never dealt with the legislative process, never gone through the sausage-making involved in turning a proposal into a law.
He is getting an early lesson in how the machinery of government is designed to frustrate a president. Democrats in Congress ultimately cannot block his cabinet nominees; they don't have the votes. But they can slow things down, as they have done with several nominees already. Imagine what will happen with controversial legislation.
Mr Trump could face resistance from Republicans as well as Democrats. House speaker Paul Ryan and Senate majority leader Mitch McConnell have been nothing but co-operative and positive toward Mr Trump since the election. But Mr Ryan's conservative vision is not fully compatible with Mr Trump's outlook, and the two are likely to clash.
Mr Trump has sent mixed signals about issues, another complicating factor. He's for repealing and replacing the affordable care act, but he told 'The Washington Post' that he wants everyone to be insured under a replacement. Some Republicans would like to repeal and eventually replace. Mr Trump has backed them off by saying the replacement will coincide with the repeal. That's just one example.
"From this day forward, a new vision will govern our land," Mr Trump said in his address. "The time for empty talk is over." The question is, can he actually deliver?
Dan Balz is chief correspondent at 'The Washington Post'. He has served as the paper's national editor, political editor, White House correspondent and southwest correspondent