SIMI VALLEY, Calif. — Political and Hollywood heavyweights from past and present mourned and reminisced over a bygone era at the funeral of Nancy Reagan — a reflection of the unique and enduring cultural sway held by the former first lady and her husband since their era in the White House.

They talked of her signature elegance and the fierce approach she took to her causes.

But most of all, they talked of her marriage and ferocious love for her husband that eclipsed all else in her life.

The Reagans were “defined by their love for each other,” said former Secretary of State James Baker at the service.

While her husband was alive, she was fiercely protective of every aspect of his life and career, Baker said.

After her husband's death, she dedicated herself just as relentlessly to President Ronald Reagan's memory and place in history, he said.

Baker said the two were “as close to being one person as any person could be.”

Daughter Patti Davis said, “My parents were two halves of a circle. Nobody truly crossed the boundaries of the exquisite space that was theirs.”

Davis made brief reference to her at-times bitter relationship with her strong-minded mother and recalled the heat of her wrath.

“Even God might not have the guts to cross Nancy Reagan,” she said.

Davis said that so deep and visceral was her mother's love for her father, that her mother felt haunted for weeks after his death, hearing his footsteps down the hall, seeing him at the foot of her bed.

She described “the circle of their own private world, — indestructible, impenetrable, an island for two.”

The funeral, an invitation-only affair at the Ronald Reagan Presidential Library, was attended by representatives of 10 White House families.

Shortly before the funeral began, former first lady Hillary Clinton and Caroline Kennedy could be seen helping former first lady Rosalynn Carter find her place between them in a history-filled first row.

Sitting with them was first lady Michelle Obama; former President George W. Bush and his wife, Laura; Tricia Nixon; and Lynda Byrd Johnson Robb and Luci Baines Johnson.

The guest list read like a flashback to a bygone era, with celebrities like Wayne Newton, Anjelica Huston, Melissa Rivers, Tina Sinatra, Bo Derek and Ralph Lauren.

Mr. T, a stalwart ally in Reagan's “Just Say No” anti-drug campaign, arrived through a side entrance dressed in full camouflage attire, combat boots and an American flag wrapped around his head.

“They had a magnificent sense of occasion. They had style and they had grace and they had class,” said Brian Mulroney, Canada's prime minister when Reagan was president.

In one of the most poignant moments of the service, Mulroney read a 1981 love letter — one of many in their lifetime — that Ronald Reagan wrote to his wife.

“For there could be no life for me without you,” the letter read. “I love the whole gang of you — Mommie, First Lady, the sentimental you, the fun you and the peewee powerhouse you. Merry Christmas you all — with all my love. Lucky me.”

The funeral brought together under one tent notable Democrats and Republicans at a deeply divisive time, from former House speaker Newt Gingrich and former California Gov. Arnold Schwarzenegger to House Minority Leader Nancy Pelosi.

Over the past two days, more than 4,500 have flocked to this library in the Simi Valley to pay their respects to the former first lady ahead of the funeral, and many continued to stream in Friday morning before the service.

On a cool day in the valley with clouds overhead, the guests emerged one by one from a cavalcade of black luxury vehicles.

As they walked up the library's gravel path toward a vast white tent, the Topatopa mountains loomed in the background.

And many reminisced nostalgically not only about Reagan but the American era she represented.

“One of the last great grande dames,” said television host Melissa Rivers, who recalled the countless conversations between Reagan and her fashion maven mother Joan Rivers. “She was an elegant, wonderful woman.”