By Kevin Connolly
BBC News, Washington
It is not easy to find a way of conveying either the sheer scale of the American economy - or the depth of the hole into which it is sliding.
President Obama has adopted a more sombre tone since taking office
Take the trillion-dollar deficit, for instance - does it help you to know that if you drew that out of the bank in $1,000 bills and stacked them on top of each other, the pile would be 63 miles high?
Or the cost of the $787bn (£541.5bn) Obama stimulus programme - do you have a firmer grasp of its scope if you are told it is the rough equivalent of spending a million dollars a day from the moment Christ was born all the way through to the present day?
Probably not - which gives you a sense of the task that Barack Obama faces on Tuesday night when he addresses the joint houses of Congress on Capitol Hill.
He must try to set America's problems in perspective, and even seek to lift the eyes of his audience to the opportunities that he must surely believe will lie beyond.
Test of vision
Mr Obama has, of course, been highly visible in his first month in office.
He believes in government, unlike his predecessor, and he believes in himself.
So there have been big set-piece speeches all over the country, and a live televised news conference as well.
But this will be a test of vision, in the imposing arena of the House of Representatives chamber.
It will look and feel like the State of the Union addresses which normally come at around this point in the political calendar (generally a little earlier than this).
But because Mr Obama is new to office, and therefore not in a position to take responsibility for the triumphs and disasters of 2008, this will be billed simply as an address to the joint houses.
No-one who heard Mr Obama's soaring exhortations to hope on the campaign trail would ever have imagined that he would have this capacity for businesslike realism
That, though, is a mere constitutional technicality; Americans will look to their energetic new president not just for a realistic assessment of their problems but for some sense of when they might hope to see recovery.
A wounded and worried America will hope for re-assurance and inspiration.
A kind of hunger for hope among the American people was part of the mixture which fuelled Mr Obama's campaign - it will be interesting to see how much hope he feels he can offer as he reflects on the state of the nation a month or so after his inauguration.
In that month he has governed as he campaigned - taking his message to Colorado, Florida, Indiana and Arizona and talking directly to voters.
His assurance on stage and his easy mastery of live television are powerful tools for a leader.
And he has been busy.
There is a package of help for homeowners, and of course that stimulus programme of $787bn of tax cuts and spending increases.
There is even more bailout money for banks (although he offers much tougher love to the good people of Wall Street than they got from George W Bush).
But his tone has been serious, often rather sombre, and every speech is peppered with references to the crisis and to the difficult days ahead - how things will get worse before they get better.
Looking back, that new rhetorical mood can be traced back to his inauguration speech, which had stirring moments in it, and which rang with determination, but which struck me as rather dark in tone.
Economic pain is being felt across the US
No-one who heard Mr Obama's soaring exhortations to hope on the campaign trail would ever have imagined that he would have this capacity for businesslike realism, but there it is.
There are some people who even wonder if Mr Obama is not rather overdoing the grim sobriety - whether it may be time for some slightly sunnier allusion to the better days that lie ahead.
The American people still like Mr Obama - but their appetite for being warned by him about the direness of their predicament will not be infinite.
And there will be plenty to watch out for in the content too.
If the pure toe-to-toe partisan slugfest of American politics is your thing, then look out for any reference from Mr Obama for the need for more bipartisanship on the Hill.
It is true that most presidents come into office singing this tune to some extent, but Mr Obama made more of a point of it than most, and when push came to shove only three of the 219 Republicans on Capitol Hill supported his stimulus package.
True, this speech is about the economy - but might there be some wistful passing reference to the desirability of the Folks Who Live on the Hill trying to get on a bit better?
And it will be interesting to see exactly how he pitches that economic message too.
He has begun his four-year term with an explosion of spending and borrowing which he argues is necessary to jolt the economy out of recession.
Now he says he intends to finish that term with the budget deficit reduced to less than half its current level.
He has argued that eliminating waste, taxing the rich and cutting back in Iraq will do the trick, but it is hard to reconcile the big-spending Mr Obama of this deep recession with the fiscally conservative figure he intends to cut in a few years time.
It will be riveting political theatre if he has the political courage to sell the idea of fiscal discipline to a country which has got used to living beyond its means, at the very moment when the economic pain is at its most acute.
So take it with a pinch of salt when they tell you this is not quite a State of the Union address.
It really might as well be.