The old adage that when you've got nothing nice to say, it's best to say nothing at all is good advice for the US president, Barack Obama, as he prepares his Arab Spring speech this week. The address, to be delivered on Thursday at the State Department, has been billed an attempt to "reset" relations with a fast-changing Arab world bitterly disappointed by his failure to deliver on the promises of his last such speech, in Cairo two years ago.
The pursuit of dignity, justice and progress highlighted in Mr Obama's Cairo speech have, of course, been central themes of the Arab Spring, but many have found the US hesitant to support democracy when friendly tyrants such as Hosni Mubarak were falling, and then backing the harsh crackdown by allies in Bahrain but confronting repression by Col Muammar Gaddafi and being caught somewhere in between on Syria.
Mr Obama responds to Arab rebellions case by case, but he may have a hard time selling Arabs on that strategic-realist logic. If anything, his administration has managed to alienate both Arab democrats - by appearing inconsistent - and Arab autocrats, who see him as having betrayed Mr Mubarak.
In short, the Arab world may not be much interested in Mr Obama's grand narrative of events in the region. And he'll invite derision if, as White House aides have told the media, he ties it to the death of Osama bin Laden. Bin Laden is in some ways more of an American issue than an Arab one; his death a footnote rather than a milestone in the pages of the region's history.
Where Mr Obama really runs into trouble, though, is on the promises he made in Cairo to prioritise justice for the Palestinians by resolving their conflict with Israel via a two-state solution. No US president had spoken as passionately of the plight of the Palestinians: "For more than 60 years they've endured the pain of dislocation," Mr Obama said.
"Many wait in refugee camps in the West Bank, Gaza, and neighbouring lands for a life of peace and security that they have never been able to lead. They endure the daily humiliations - large and small - that come with occupation. So let there be no doubt: The situation for the Palestinian people is intolerable. And America will not turn our backs on the legitimate Palestinian aspiration for dignity, opportunity, and a state of their own."
Mr Obama urged the Palestinians to abandon violence and instead adopt the tactics of nonviolent protest championed by America's Civil Rights movement. And he bluntly demanded that Israel halt settlement activity, the "legitimacy" of which he said the US does not accept.
It would not be an overstatement to say that the president failed catastrophically to deliver on those lofty words, his approval ratings in the Arab world plunging precipitously as he caved in before the Israelis on the settlement issue.
Mr Obama was the last hope for reviving the moribund peace process, but he was unable to find the will or the means to pressure Israel to heed US demands. The resignation last Friday of Mr Obama's Mideast special envoy, George Mitchell, was the bureaucratic equivalent of a death certificate for the prospects of a negotiated peace between the current Israeli and Palestinian leaderships.
Mr Obama's dead end has, in fact, spurred the Palestinian leadership to break free of Washington by taking their case to the UN, and also through the reconciliation between Fatah and Hamas, both over US objections. Young Palestinians have also begun to embrace the unarmed defiance tactics of the Arab Spring, as in last Sunday's border protests.
The White House has warned ahead of Thursday's speech that the Israeli-Palestinian conflict is not going to go beyond maintaining the status quo. Too bad, really, because in the eyes of the Arab world, the Israeli-Palestinian conflict remains a key litmus test of US bona fides - as Mr Obama's own military commander's have long warned.
Mindful of the needs of his re-election campaign, Mr Obama is hardly about to start a new fight with the Israelis. He learned his lesson on the settlement issue, where the Israeli prime minister, Benjamin Netanyahu, mustered enough support in the US among political allies needed by Mr Obama to force the White House into a humiliating retreat. Instead, Mr Obama plans to make nice. He welcomes Mr Netanyahu to his office this week, and next weekend the President will address the annual congress of the America Israel Political Action Committee (AIPAC), the flagship Israel lobbying organisation in Washington.
Don't expect Mr Obama to say anything on Thursday that would antagonise the Israel lobby just days before showing up at its gala event to demonstrate his loyalty and shore up domestic political support.
The problem with the Arab "reset" speech, really, is that Mr Obama doesn't have much to offer on some of the key concerns of the very Arab public to whom he is ostensibly reaching out. Osama bin Laden is irrelevant to them. So are the president's expected warnings about Iran's nuclear programme - a theme more likely to endear him to Arab autocrats than to their newly empowered publics.
So, if the purpose of the speech is to align the US with the momentum of the Arab Spring, there's no good reason for making it now - it's not as if Arabs are waiting by their radios to hear what Mr Obama has to say. And there's greater likelihood of a speech that further increases Arab frustration with Washington.
Much as he loves to talk, this time President Obama may well be better advised to make his next big speech to the Arab world only when he has more to offer than platitudes.
Tony Karon is a New York-based analyst. Find him on Twitter @Tony Karon