Editor's note: CNN Contributor Bob Greene is a best-selling author whose new book is "Late Edition: A Love Story."

Bob Greene says ordinary life stops when Muhammad Ali appears anywhere.

(CNN) -- It was still early enough in the evening that the main dinner crowd had not yet started to show up; the restaurant, east of Michigan Avenue in Chicago, was less than half-filled.

The party of 10 at the table by the front window had arrived promptly for their 6 p.m. reservation. Nine of the 10 studied their menus, but the 10th, the man at the head of the table, did not.

Muhammad Ali, 67, stared down toward the white tablecloth and drew on a piece of paper. He sketched a picture of a mountain.

There are a handful of men among us who, simply by appearing out of nowhere, make other men and women pause involuntarily to consider the long paths of their own lives. It is as if these men have always been with us, and if you should unexpectedly spot Bob Dylan in an airport, if you should see Paul McCartney walking through a hotel lobby, if you should encounter Sean Connery entering an office building, it will bring you up short. It's like opening a diary, even if you have never met them, even if you have never seen them except on a television set or a movie screen.

Yet Ali is different even from them. Ali -- his story so complicated, his health failing, his imprint on the world so indelible -- makes people mist up the moment they lay eyes on him. It was happening tonight inside this restaurant called the Rosebud Steakhouse; diners at their own tables, not quite sure for a second that they were really seeing what they were seeing, let their gazes linger and could not look away.

Ali drew.

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The other men and women at his table -- this was a gathering of family and friends to celebrate a birthday, and Ali had come into Chicago from his farm in Michigan -- talked animatedly and laughed. Ali did not speak. He wore a blue-and-white Hawaiian-style shirt; someone had tucked a white napkin into the space above the top button.

Over the speaker system of the restaurant, a slowed-down acoustic knockoff of the old Tom Petty hit "Free Fallin' " was playing softly:

"She's a good girl, crazy 'bout Elvis ..."

A family, across the way, talked spiritedly among themselves. They were deciding something.

The father and the children stood up.

From the ceiling, the song:

"... and I'm free, free fallin' ..."

They walked over to Ali's table.

"We apologize for the intrusion," the father said.

Ali looked toward them, showing a gentle expression.

The father had a camera. He said to his children: "This is the most famous face in the world."

It is difficult to know what the children made of this. Youth and strength and beauty are so fleeting. The man in the Hawaiian shirt once embodied all of those things, before these children were born. Three times the world heavyweight boxing champion, the center of global fascination and frenzied controversy after winning his first title and then changing his name from Cassius Clay, endlessly mesmerizing with his float-like-a-butterfly, sting-like-a-bee ring style, called "the greatest of all time" so often that the words became almost an official designation, the sight of his flawless face and the sound of his confident-beyond-all-dispute voice a sustaining part of the very atmosphere. ...

But his road has turned hard, and here were these children, who were not around for any of that, standing with their father next to the table.

Ali's family members and friends said it would be all right for the father to take some photos, so he did. When he left, Ali went back to his drawing.

More diners were beginning to arrive at the restaurant. Their evenings changed the moment they caught sight of him. Some pulled out cell phones to call people across the nation; others quietly debated whether to approach him.

Many years ago, I traveled the country with him to prepare a magazine profile for a special issue on the 50 men and women judged to have had the greatest impact on society during their time on Earth. Everywhere Ali went, he was mobbed; people grabbed at him, people cried out, people attempted to touch his face. In the middle of all this one day, he said to me, almost in a whisper:

"This is the whole world. This is what my whole life is like."

That hasn't changed, although his ability to speak aloud about it has.

The food began to arrive at his table. The people to his right and to his left helped him with his. He demonstrated not the least sliver of self-consciousness; this is part of his life now, and he knows how much he is loved.

He handed something to a man named Cleve Walker, who has been his friend for 50 years.

It was a drawing that a young girl had brought over to him earlier. She had made a picture of a butterfly and had presented it to him.

Now Ali gave it to Walker, who took it across the restaurant to where the child was sitting with her family. Ali had signed his name to it. Walker handed it to the little girl. Her face lit up.

Outside the restaurant, on Walton Street, a group of young men walked by, wearing officially licensed jerseys bearing the names and uniform numbers of their favorite current-day sports stars. One of the young men glanced through the windowpane but did not register that the man at whom he was looking was Ali.

Ali studied the tablecloth, and a birthday cake arrived, and the others at the table began to sing in the direction of one woman among them:

"Happy birthday to you, happy birthday to you ..."

Ali did not sing nor did he look up. But then the others reached the penultimate line of the song:

"Happy birthday, dear Marilyn ..."

And with that Ali lifted his head and gazed directly at her, right into her eyes, and smiled the most luminous smile toward her.

"... happy birthday to you."

Soon they rose to depart. Some in the restaurant, now more crowded, applauded. Ali did not react.

And then he was out on the street and in a moment out of sight. Around the next corner, although they did not yet know it, people would soon be stopping in their tracks. He may be the only one who remembers his life when it was any other way.

The opinions expressed in this commentary are solely those of Bob Greene.

All About Chicago • Muhammad Ali