To understand empty in its physical enormity, fly over the Empty Quarter of Saudi Arabia: thousands of square miles of sand, untrammeled by man or animal. Awesome.

To understand empty as a metaphor, look at this past week in Washington.

Glenn Beck summoned his flock to the Lincoln Memorial last Saturday and offered them quasi-religious platitudes with a strong dash of patriotism: God and country. Empty concepts without a purpose to back them up.

The tens of thousands, quite possibly hundreds of thousands, of Beck adherents who filled the Mall already have God and patriotism. They did not come to be converted: They are the faithful, even if Christopher Hitchens, writing in Slate with awful clarity, described them as self-pitying white people.

But the emptiness was not confined to the disappointing words from Beck, once Rupert Murdoch’s Man on Earth, now employed, it would seem, as God’s man down here.

On Monday, President Barack Obama made a brief — so brief it was almost furtive — appearance in the White House Rose Garden to push for tax cuts for small business and to chastise the Republicans in the Senate for bottling them up. Nothing new here. More emptiness.

Come Tuesday, it was the withdrawal-from-Iraq prime time broadcast for the president. But it had no passion, no conviction, no phrase to savor.

On Wednesday, Obama was back in the Rose Garden, talking up Middle East peace. Reporters are getting so used to this frequent use of flower power in the Rose Garden that many prefer to listen to the president from the relative comfort of the seats in the press center. In the East Room, reporters heard more platitudes about the hard path ahead to achieve peace.

It has become pretty hard just to listen to this stuff as successive presidents have sought to catch the ultimate brass ring of diplomacy. The “peace process” has become itself an empty formulation.

There has been such emptiness in the political debate that partisans are busy inventing bogeymen to run against. The gun lobby, which sends out incessant e-mail, has a whole series of horrors it has minted for gun lovers to worry about. Would you believe that, according to the lobby, Obama is in league with the United Nations to confiscate American weapons?

Others of the right see creeping “European-style socialism” about to get us. Being an empty threat, we are not told what this perversion actually is and how we would be able to recognize it when it gets here. Will it make us like England or France or Germany? One trembles.

On the left, where the hopper of ideas is as empty as it is on the right, there is paranoia and betrayal. Paranoia that the right wing and its insuperable ally, the Fox News Channel, are going to sweep into power, winning the House and Senate in November and the presidency in 2012, after which all the good things of the 20th century, like Social Security, Medicare, Medicaid, mutual insurance companies and credit unions, will be privatized and handed over to the people who used to run Lehman Brothers. Reproductive rights, gay and lesbian rights, and maybe some civil rights legislation will be swept away as the country is ceded to a duopoly of oligarchs and fundamentalist Christians.

All this because these are empty times. These are empty years and an empty decade, where all the old ideas contend only because of the paucity of new ones.

This hollow sound and fury comes when, in really profound ways, the world, and especially our corner of it, is changing — or, to use the word of the day, being “reset.” Copper wire is being retired for wireless, paper for computer screens, oil for electricity. The global climate is changing. Europe has become China’s largest market. And the oldest currency of all, gold, is flourishing.

Only the desert is really empty and that, too, is an illusion — it is a live, moving thing with microbial life, shifting dunes and even fauna and flora that the inexperienced observer does not see.

Our political rhetoric is empty, vacuous and vapid, but things are happening. Profound, ignored changes are underway.