On Tuesday, January 20th, Barack Obama will take to a specially-constructed stage on the steps of the United States Capitol, and history will be made.

It will be a defining moment for the United States and the world. A moment that will be recounted for years to come, no doubt; a moment we are sure to remember.

And then Obama will make his first speech as the 44th President of the United States.

Inaugural addresses are judged by the highest of standards. Since Obama is famed for his speeches, and since the challenges the world faces are great, he will be judged perhaps against higher standards than many of his predecessors. Bluntly, he has to nail it.

I’ve been reading and watching a fair few past inaugural addresses over the last week. I’ve also read quite a bit by Peggy Noonan – an American conservative commentator whose approach to the issues I rarely agree with, but whose ability in speechwriting can hardly be disputed. Amongst others, she wrote for Reagan.

Here’s what I think.

Obama has two things to do when he reaches the podium. First, define the moment. The speech has to paint for the audience a clear picture of now — what the world is like, what that means for the country. He must answer the question: which are the big themes and trends at play at home and around the world today?

Second, the new President has to sketch for the American people what must happen next – how best to proceed, how to meet the challenges. He must articulate his vision for the future of the United States. What will we do tomorrow? How do we use these next four years to restore America’s promise?

There’s a wider point to be made: Rhetoric can make a good speech great, but it can’t produce substance, meaning, emotion from the ether. The power of a speech lies in what it says, the argument it makes — simply, what it means. It’s that which makes it emotive. Good writing can amplify that; great writing can can make crowds come to their feet. But it is no replacement for the cogency and logical force of what’s being said; no replacement for meaning.

Take Churchill. “Never in the field of human conflict was so much owed by so many to so few.” Incredible, and moving too. But it’s powerful not just because of the sentence structure. It’s deeper than that. It’s what he’s saying: People have died so that we can be safe; we owe them.

Kennedy’s inaugural address wasn’t brilliant for (what Noonan refers to as) its ‘ask-nots’, brilliant though they were. It was brilliant because what he said was powerful in the moment. In the face of a deepening cold war divide, of insurgencies throughout the world, it was not so much a call to arms as a call to join arms. To unite — and, looking danger in the face, stare it down, unflinching in the desire not for war but for peace. Kennedy spoke of the universality of the rights of man, and affirmed his commitment to use the power of the United States to protect and promote them at home and abroad.

Thought by many to be the best of the modern inaugural addresses, it was so because of what it said; because of what he meant.

The worst inauguration address of recent times is thought to be Bill Clinton’s second. Clinton is often referred to as ‘the great orator who never gave a great speech’. He was (and remains) impressive in interviews, and on the stump campaigning. Simply, he is naturally very adept at conveying his feelings clearly, sincerely, believably. But he is not that good at giving prepared, set-piece speeches. He seems to try to adopt the persona of somebody else — unnecessarily — which is not so convincing.

But that wasn’t the problem in this instance. The problem with his second inaugural was it said nothing of real note. Rhetorically it was impressive, but it was all tinsel and no tree. Watching it, when you reach the end, you have trouble working out what he said. A Presidential inaugural shouldn’t be overloaded with policy detail, but it should paint a clear picture of what the administration will stand for, how it will proceed. Clinton set the scene too much, painting a distant landscape with no real subject to occupy the foreground, no real vision. It was what a Presidential inaugural address must not be.

Obama will avoid Clinton’s mistake by doing the following. First, explain how he conceives this moment and its place in history. Second, and most importantly, put forward his vision; what government must do and be in the next four years in America.

He was smart to give his big economic speech last week — it got the nitty gritty out of the way. It means his address next Tuesday need not be so specific, nor focussed upon a single issue; he will be able to articulate his vision in broader brushstrokes. It must, however, be a perspicuous vision. It can’t just be a string of good phrases.

As for us, we will reach the end of his speech moved. The test will be if we know clearly what his big message was.