The smell of incense hung in the air from Midnight Mass, where hundreds of people, a full choir, and an orchestra had come to St. Clement's Episcopal Church in Center City to celebrate a Haydn St. Nicholas Mass.

But now, it was 7:45 on Christmas morning, and the Rev. Gordon Reid was at the altar with only empty pews behind him, making his personal offering before the start of the Low Mass of the Dawn, the second of three Christmas Masses.

Just six people - four men who came alone and an engaged couple - attended the 8 a.m. Mass, a humble liturgy often overlooked, sandwiched between Midnight Mass and the 11 a.m. High Mass of Christmas.

Also known as the Shepherds' Mass, this quiet Christmas service is the only one in which the name of the martyr St. Anastasia, beheaded on an Italian island in the early fourth century, is invoked.

In the Dawn Mass, there is no singing or sermon, no direct address to those in the pews. In the echoing of the old sanctuary of St. Clement's, at 20th and Cherry Streets, the liturgy is spoken in a soft murmur from the front right corner, the Lady Altar. It lasts 27 minutes.

"Jesus came into the world in quiet, in the hush. It's kind of symbolic to that," said parishioner Marcello Rivera, 53, of Northern Liberties. He said he had intended to go to Midnight Mass, but could not make it in the hustle of Christmas preparations.

"It spares me sermons," joked Robert Regan, 70, a retired professor of 19th-century American literature at the University of Pennsylvania, who supervised the plate collection. "No music, no sermons. My wife doesn't come, and I don't want to fritter away the rest of the day. It is a very quiet Mass. High Mass tends to run two hours."

Those attending the Dawn Mass said they appreciated the simplicity of the service, the portrayal of the humble shepherds from the Gospel of Luke as rushing to the manger and then telling what they had seen and heard of the baby Jesus, while Mary "kept all these things and pondered them in her heart."

They found an early-morning peacefulness in a church whose only sounds were the priest at the altar and the creaking of the century-and-a-half-old wooden pews.

"It has a very devotional aspect," said Paul Goings, 41, a computer programmer from Ridley Park, who attends all three Masses on Christmas to experience "the fullness of the Christian celebration."

"We've got guests coming," explained the only woman at the Mass, who attended with her fiancé. They gave their names only as Stephanie and Bruce. He added amiably, "I've still got cooking to do. It's a long day."

St. Clement's, an Anglican Episcopal church that is seeking an assistant priest, prides itself on a traditional liturgy. The Dawn Mass, which many churches skip, is in keeping with that.

As such, the martyred Anastasia, a healer of prisoners thought to have been crucified, burned, and beheaded on the island of Palmaria, gets her due.

This second Mass of the day was originally celebrated not in honor of the birth of Jesus, but in commemoration of Anastasia. "It's the only Mass in which you mention her and ask for prayers for her," said Reid. "You ignore her in the Midnight Mass. It's the only place you fit her in."

And so, after opening with "Light shall shine upon us today: for unto us the Lord is born," Reid and the altar server, Martin Peiker, recited the prayer for Anastasia: ". . . may by her effectual intercession be holpen in thy sight. Through the same. Amen."

The Mass of the Dawn is a bit like Linus in A Charlie Brown Christmas, standing apart from the hubbub and pageantry of the holiday: pure and unadorned, echoing the gospel in the quiet of a misty morning of melting snow outside the church, where two winter robins flew around the tree branches outside the door.

"Last night was a three-ring circus," said Goings, who didn't get home until 3 a.m, but was back at the church at 8. "It makes for a long day, but it's very satisfying. It's the only day when all three are different."

The traditional way of saying Mass is making a comeback in the Episcopalian and Roman Catholic Churches, said Reid. He said he has letters from priests who use St. Clement's services and pictures "to get it right." "There are a lot of new, young people coming, which feels odd. You'd think it would be old people who would be conservative and like the liturgy, but a lot of young people like the Gregorian chants," he said.

After completing the Mass at 8:27, Reid hurried to the clergy house to prepare breakfast for six friends visiting from Scotland. Soon enough, it would be time for the High Mass, at which many more people, content with their Christmas dawn rituals at home, would attend.

Reid expected about 12 people at the early Mass, but the turnout of six was no worry. Unlike some religions, there is no required number. "We will do it for one," he said. And, of course, for St. Anastasia.

Contact staff writer Amy S. Rosenberg at 215-854-2681 or arosenberg@phillynews.com.