The crowd in front of City Hall on Thursday had a different vibe. It was there to watch the arguments before the state Supreme Court on the constitutional amendment banning same-sex marriage. There was a big screen television, and the usual cast of characters showed up - the sign-holders, the costumed and the guys yelling out the windows of pickup trucks.

But there were others. Kids, couples, families. This debate is moving, quicker than a lot of people realize, away from political posturing.

Proposition 8 supporters would disagree with that. But here's some bad news for them.

It is worse than they think. They might think the gay and lesbian community has been behind the marriage cause all along. In fact, it is only beginning to unite.

"Ten years ago, this (debate) was about rights and benefits," said Mike Marshall, a political consultant. "Thursday it was about love, commitment and family."

Marshall walked through the crowd on Thursday in a happy daze. In 2000, he spearheaded the campaign against Proposition 22, the ballot initiative that defined marriage in state law - but not the Constitution - as being between a man and a woman. There was certainly a core of support for those opposing Prop. 22, but Marshall admits that he sometimes felt as if he was tilting at windmills.

After all, this was a time when the American public tended to nervously giggle when it was mentioned that someone might be gay.

"The view (among gay and lesbian politicians) was, let's don't fight this because there is no way in the world we are going to win and we will look bad," Marshall said.

The idea persisted. In 2004, then-Assemblyman Mark Leno (now a state senator from San Francisco) introduced a marriage equality bill to the rousing sound of one hand clapping from the gay and lesbian community.

"Let's just say there was a lack of consensus," Leno said. "The debate within the caucus was, 'Why are we doing this?' "

Again, the point was the concept was a loser, it could only hurt the cause for legal rights for domestic partners, and in a presidential election year it might damage Democratic chances. The pushback was so strong that Leno agreed not to bring the bill to the floor in 2004.

He let the bill expire quietly in committee in February and then returned to San Francisco. It turned out to be the first weekend of same-sex marriages in the city.

"And," said Leno, "the world changed."

Leno brought the bill up again in 2005, and it passed both houses. It was clear that things were starting to turn, even though the governor vetoed the bill.

Leno remembers talking to a public official, a lesbian, who was among the opponents of his marriage bill.

"The possibility of marriage was so distant to her that until she saw it happen - same-sex couples were on TV all weekend long - she couldn't even imagine it," Leno said.

James Hormel, a 76-year-old San Franciscan who is heir to the Hormel meat packing fortune and a generous donor to the same-sex marriage cause, lived what used to be a "typical" life for a gay man.

"I actually went through the charade," said Hormel, who is writing a book about his experiences. "I was married, I had five children. I did my damndest. There is an undercurrent in the gay community, which is still there in some cases, of not being worthy."

That's not the case with younger gay men and lesbians.

"The younger generation, the twentysomethings, are very clear," Leno said. "They want to settle down, have a family and have kids."

It may seem like a subtle shift, but the implications are huge.

"I have a fair number of friends who are parents now," Hormel said. "Ten years ago, they never would have thought of that. Even five years ago. It really has moved quickly."

Supporters of same-sex marriage who were handicapping the Supreme Court oral arguments Thursday were not very optimistic. But, almost as an afterthought, most said they expected the judges to uphold the marriages of some 18,000 same-sex couples who were married last year.

Really? Can you imagine that happening back in 2000?

"It is just a foot in the door," Hormel said. "But it is a big foot in the door."

Here's a prediction. Although those 18,000 couples are still married, the fabric of society will not rupture, heterosexual marriages will not collapse, and elementary school students will not suddenly become gay.

In fact, I bet there will be a surprise for all of those who are still railing against the earth-shaking changes same-sex marriage will bring to their lives. I bet it doesn't have any effect at all.