There is a Christmas story that every new member of the Church of the Holy Trinity on Rittenhouse Square learns soon after joining.
It is about two friends in 1868 - a rector and his organist - and the inspiration that grew from procrastination.
Yesterday afternoon, as church volunteers arranged sprays of red flowers around the altar and children put on costumes for the Christmas pageant, the story of the carol that put the 150-year-old church on the Christmas map was recalled by members.
"It's our claim to fame," said Soozung Rankin, a member for three years, whose 10-week-old son, Robert, was about to debut as Baby Jesus in the manger tableau.
The story begins with a trip to the Holy Land by the church's vicar, the Rev. Phillips Brooks. It was 1865, and Brooks was so moved by what he saw that he penned a poem.
O little town of Bethlehem,
How still we see thee lie.
Above thy deep and dreamless sleep
The silent stars go by.
Back in Philadelphia in 1868, he asked the organist of the church, Lewis Redner, to set the lyrics to music for Christmas. Redner worked in real estate and played the organ for four churches.
Days passed, then weeks, but no music.
With just two days before the Christmas service, Brooks anxiously inquired, "Have you ground out the music yet?"
"No," Redner assured him, "but I'll have it by Sunday."
According to Redner's diary, "On Saturday night, my brain was all confused about the tune."
He went to sleep, but woke with a start, "hearing an angel-strain whispering in my ear."
Redner scribbled the treble of the tune and before the Sunday service filled in the harmony.
"The spirit descends perhaps when we're open," said the Rev. Alan Neale, the current rector of Holy Trinity.
O Little Town of Bethlehem will be sung at all the Christmas services, giving members of the Episcopal parish a particular sense of pride.
"We sing it whenever we have the opportunity," Neale said.
Neale, a native of London who has lived in the United States for 21 years, concedes that he grew up singing a different version.
The lyrics by Brooks were the same, but the music was by the British composer Ralph Vaughan Williams. The British version sounds more like a formal hymn compared with the simpler, slower melody by Redner.
"I have to accept that in Britain, we sing the wrong tune," said the vicar. "During the singing of the carol, some will give me a knowing look that says, 'This is our tune.' "
Benjamin Leiby, the assistant organist for Holy Trinity, who also works as a bio-statistician at Thomas Jefferson University Hospital, said he did not know anything about the history of the song until he joined the church in 2001.
As a piece of music, he said, the song "is not the most upbeat of Christmas carols."
The lyrics speak of dark streets, dark nights, and cries of misery. "It's a little unusual," Leiby said. "I prefer the English tune, but we definitely don't do that here at all."
With the Christmas pageant approaching late yesterday afternoon, knee-high shepherds, angels and wise men were taking their places. Two dozen children posed before a triptych mural by the artist Hildrith Mier of - fittingly - the manger scene in Bethlehem.
Standing in the back of the church, Edward Weston, a 15-year member and head of Parish Life, said what he likes most about the carol are the lyrics.
"The words are gorgeous," Weston said. "It's a sermon in itself. It really works."
Brooks, he said, was an inspiring preacher. During the Civil War, he would ride by wagon from Philadelphia to the battleground around Gettysburg to minister to wounded Union and Confederate soldiers.
"Tonight, I will think not only about the song," Weston said, "but also the man who wrote it and what an example he was."