The heart of St. John Vianney — an Ars-France parish priest who practiced in the 1800s and was canonized in 1925 — went on display at St. John’s Seminary in Brighton yesterday, following an elaborate procession into the cathedral and a welcoming by Cardinal Sean O’Malley.

The heart has been considered a relic by the Catholic Church since 1904 when St. John’s body was exhumed and found intact, at which time the body was placed in a glass case for viewing. The body has not decomposed and is one of only a handful of saints’ bodies’ that are, for that reason, considered incorruptible by the Catholic Church.

The heart has only left France twice — once for the saint’s canonization in Venice and now for the current American tour, which started in Long Island before reaching Boston.

“This is a very historic event,” said Father Daniel Hennessey, vocations director for the Archdiocese. “For the first time ever, the relic is in the United States.”

Hennessey said the charcoal-colored heart was flown to Merrick, N.Y. a week ago where it was venerated before being delivered to St. John’s last Wednesday night.

Bishop Guy Bagnard of Ars-France escorted the heart, tucked into a velvet sack, overseas. Upon arrival, the heart was moved to a gold and velvet shrine built by the church in Merrick. From Merrick, it was driven to Brighton, where it will remain until after Sunday Mass.

According to Hennessey, “the heart will never leave the Bishop’s side.”

According to Catholic Church doctrine, the heart is a living reminder of St. John’s dedication to his parish and to God.

“In order to understand the significance of the heart, we have to understand the significance of a relic,” Hennessey said. “We venerate a relic, or mortal remains, to remind us of the love that the person had for God. Religiously, it is a reminder of the hope we all share in our belief in the resurrection of the body.”

The heart has a practical resonance as well. According to the Catholic Encyclopedia website, St. John Vianney is the patron saint of parish priests and is revered for his undying devotion to the direction of souls.

The heart’s arrival came three years after The Boston Globe reported a significant drop in aspiring priests within the archdiocese in the last decade, specifically in the last 50 years.

The heart display is open to the public from 4 p.m. to 10 p.m. Saturday and 9 a.m. to 2 p.m. Sunday.