St. Patrick’s tooth.

Justin Bieber’s hair clippings.

The bloodstained gloves that Mary Todd Lincoln carried to Ford’s Theatre.

What do they have in common?

They are relics ― prized keepsakes, preserved because of their association with significant people and events.

Bieber fans who line up for hours to peer at a lock of the teen idol’s hair inside its autographed glass case share a common desire ― on a deeper level ― with tourists who stop to see Mary Lincoln’s gloves at a museum in Springfield, IL, and religious pilgrims who make the journey to Dublin to venerate St. Patrick’s tooth.

They’re all seeking a physical connection to greatness.

“It is that same longing to connect on a physical and not just spiritual level that draws the faithful to the tombs of the saints, the houses where they lived, the altars before which they prayed, even the prisons where they were tortured,” author Thomas Craughwell writes in his fascinating and surprisingly entertaining new book, Saints Preserved: An Encyclopedia of Relics.

Craughwell, the author of several books, including 2006’s delightful Saints Behaving Badly: The Cutthroats, Crooks, Trollops, Con Men, and Devil-Worshipers Who Became Saints, writes a monthly column on patron saints that runs in Catholic newspapers around the country.

His years of research led to his latest book, which catalogs 350 of the most famous, interesting or just plain odd relics on display at Catholic institutions around the globe.

Make no mistake, though, Saints Preserved is not a stuffy historical account or pious index of which relics are where. Craughwell has a marvelous sense of humor that shines in his breezy ― and fascinating ― descriptions of the relics, their provenance and the relic-enthusiast subculture, if you will.

“Anyone who thinks that the cult of relics of the saints is itself a relic of the Middle Ages should log on to eBay,” Craughwell writes. “On any day of the week the online shopper will find a thriving business in the sale of relics, ranging from dust from the tomb of Christ to splinters of the True Cross to bone fragments of countless saints.”

Among the relics Craughwell describes are:

  • the relics of St. Bibiana, preserved inside an alabaster urn beneath the high altar of the little Basilica of St. Bibiana in Rome, near a column that is said to be the one to which executioners bound her before scourging her to death. St. Bibiana is invoked against hangovers. Yes, hangovers.
  • the Holy Prepuce (a.k.a foreskin) of Jesus, which, according to legend, was given in 800 A.D. to Pope Leo III by the Holy Roman Emperor Charlemagne. It was housed in Rome’s Lateran Palace until 1527, when it was stolen by a German soldier during the sacking of Rome by German Lutherans and Spanish Catholics. The Holy Prepuce and its silver reliquary wound up in Calcata, Italy, where every Jan. 1 it is carried in procession during the Feast of the Circumcision of Our Lord and, as Craughwell writes, “exposed at the village church for public veneration.”
  • the head of St. John the Baptist, which was one of the most coveted relics of the Middle Ages ― when relics were big business, not all of it on the up-and-up. That may explain why no fewer than nine different religious sites claim to house it today, including a church in Rome, a cathedral in France, a monastery in Armenia and the Umayyad Mosque in Damascus.
  • boards from what is said to be the Holy Manger where Jesus was born to the Virgin Mary in Bethlehem, which are kept in a large gold, silver and crystal urn in a tiny chapel below the high altar in Rome’s Basilica of St. Mary Major.
  • the body of little-known St. Zita, a 13th-century Italian saint, which lies in a glass casket in the Basilica of San Frediano, in Lucca, Italy, where she attended Mass every day. Deeply pious all her life, Zita was just 12 when she was hired as a servant for a wealthy family and would get up before sunrise to attend Mass next door to her master's house. One day she put bread in the oven before going to Mass and became so caught up in prayer that she lost track of time. It is said that when she rushed back to the kitchen, she found perfect loaves cooling on the table ― angels had tended to her baking while she prayed. She is the patron saint of housekeepers and waitresses.

Visiting these relics, Craughwell explained, is akin to visiting the grave of a loved one, or cherishing a family heirloom.

“The shrine or relic is a physical link with someone who was faithful to God in this life,” he said. “Bringing out Grandma’s china for Christmas dinner stirs the emotions and makes us feel connected once again to someone we loved but who has since died.

“Relics work in the same way but more intensely, because ... the connection is not only to someone we love but to someone who was genuinely holy.”