Like everyone paying attention to the epic political power struggle going on in Iran, we'd heard there was to be an opposition rally in the afternoon.
Then we heard there wasn't, because it had been declared illegal by the Interior Ministry. Anyone who marched could expect to face the riot police and their truncheons… or worse.
Then, suddenly, there was. The word flowed in digital streams from cell phone to cell phone, computer to computer — and, of course, from mouth to mouth.
Now. Come. Everyone. We're marching from the University to Freedom Square.
We drove as close as we could, then — stuck in crawling traffic — we abandoned the car and began to walk. It was like being part of a vast migration — absurdly, it occurred to me, like wildebeests pouring across the veld. Thousands upon thousands of people — most of them young, but not all — heading toward Tehran University.
There was no party atmosphere like we'd seen every night in the streets during the election campaign. Nor were there angry chants or fist-pumping — the kind of defiance that had provoked riot police to attack groups of protestors over the weekend.
Instead, this was a relaxed, quietly happy crowd. Also, incredulous. Because as the procession grew, and grew, and grew, it became obvious the riot police had received instructions to stand back and let it happen.
Then, the defeated opposition candidate Mir Hossein Mousavi, who hadn't been seen since election day, drove slowly into the crush.
With neither stage nor giant speakers, few in the crowd could see or hear him. Clinging to his 4x4 vehicle, he shouted into a small handheld microphone: "We won't give up." (pictured above)
He told those close by, "Our people just want respect — and for their votes to count."
This may have been Mr. Mousavi's finest hour.
On a podium, he is tedious and wooden, with little charisma.
But glimpsed like this, emerging from house arrest to be among his people — now there's a story to be told and retold until it becomes myth.
Mousavi must be wondering what he does now.
So must Iran's religious leaders, who have ultimate responsibility for political decisions.
Sadly, this quietly euphoric gathering was ruined just as it was breaking up. In an area nearby, a small group of people attacked the headquarters of the Iranian paramilitary. Shots were fired and a man was killed. That death could now easily ignite violence on a grand scale.
But still, the world shifted on its axis a little yesterday when Iranian authorities allowed protestors, 100,000 strong, to march in peace.
CBS News correspondent Elizabeth Palmer is reporting from Tehran.