His redemption by the Jesuit priests who ran the school "has bound me to St. Joe's," Maguire said.
It's not just that four of his eight adult children graduated from Hawk Hill, and that four of his 21 grandchildren have so far enrolled. It's also that Maguire's business success has enabled him to be a major and ceaselessly passionate financial supporter of his alma mater's surging expansion, including two deals that nearly doubled the size of its City Avenue campus:
Maguire has led the campaign to finance the $93 million purchase of the 36-acre former Episcopal Academy property with $15 million in personal contributions to date. It's now the James J. Maguire '58 Campus.
"I stopped my car in the middle of City Avenue first time I saw that sign," he says.
Maguire also gave the first $2 million toward the $10 million that St. Joe's has agreed to pay for the neighboring nine-acre Archdiocese of Philadelphia cardinal's residence. That property could enable the university to increase enrollment even more than the larger Episcopal property.
Maguire's wealth and his ability to be a benefactor to his beloved university comes from insurance. He founded Philadelphia Insurance Co. Members of his clan still hold key jobs, but Maguire sold his family's share in the business four years ago for $1 billion.
Maguire began selling insurance after he graduated from St. Joe's. He targeted groups that big companies mostly ignored: deaf people, drivers of leased vehicles, health clubs, nonprofits. He hired varsity athletes - "high achievers" and "team players" - and rejected shaky customers.
Fellow St. Joe's graduate and donor Brian Duperreault built Bermuda-based Ace Ltd. into a world power after buying Philadelphia-based Insurance Co. of North America from Cigna Inc. in the late 1990s.
"Duperreault is a champion of discipline," Maguire said. "He wasn't a crazy competitor."
Worried that the industry is "graying," with too few young recruits, Maguire corralled Duperreault, Cigna boss Ed Hanway, and others to start an insurance education program at the university.
Says Maguire, "We tell our grads, 'You want a job, you got it.' "
"Jim's an icon of our industry," said Mike Mitchell, vice chairman of Graham Co., the Philadelphia-based insurance brokerage. "They insure YMCAs, behavioral-health organizations. ... They know what they know, and they focus on it, unlike companies that try to be all things to all people."
Maguire's sports focus applied at home: When his young children acted up or came home late, he made them join him for a five-mile run. They grew into varsity college athletes, marathon runners, triathletes.
Six of the eight young Maguires went on to work at Philadelphia Insurance, where serious running is part of the culture.
When Japan's Tokio Marine Holdings Inc. bought Maguire's company four years ago, Tokio made clear it was paying to keep Maguire's managers in place. Sean Sweeney, Maguire's nephew, remains president. Maguire's son, Jamie, is chief executive.
Japanese expatriate executives who have moved to the Bala Cynwyd office have taken up marathons and triathlons, as well.
"No one asked them to," Maguire said. "You lead by example."
Small private colleges face a shaky financial future, against tax-funded rivals and cheap online courses. Catholic institutions face a special challenge: Their feeder system has shrunk, as Catholic high schools shut down.
In the Philadelphia area, Catholic-school enrollment is one-quarter of what it was when St. Joseph's new president, the Rev. C. Kevin Gillespie, who grew up in West Philadelphia and Narberth, enrolled at St. Joe's at the end of the 1960s. By contrast, St. Joe's freshman class, at more than 1,200, is three times larger now.
Maguire has a foundation, and it backs dozens of causes. He has lately joined with the William Penn Foundation in backing the $50 million Philadelphia Schools Partnership to finance public- and privately funded schools in Philadelphia.
Maguire is also hopeful about Archbishop Charles Chaput's proposed "Faith in the Future Foundation," which would put the archdiocesan high schools under a board led by laymen.
It's a familiar model. Maguire was drafted onto the board of Cabrini College in Radnor in 1973. "They had 278 students," Maguire said. "The board was me, a Jesuit, and seven nuns. I told them, 'I know God will provide, but we have to get a lay board.' "
Maguire helped recruit it, started a capital campaign, and urged the nuns to focus on their strongest programs. Cabrini grew.
Seeking space to attract a more national student body, the Rev. Nicholas Rashford, named St. Joe's president in 1985, reached out to business and political figures, and set his sights on the neighboring Episcopal Academy property as that elite school prepared to move.
Maguire rallied donors, promising to match grants.
The acquisition, not completed until 2008, wasn't designed to make room for more students - neighbors and Lower Merion Township did not want that traffic. Much of the ground is newly improved playing fields.
Gillespie backs plans to use those facilities to attract star athletes and other specialized students to apply to St. Joe's. He wants to boost yearly applications for 1,200 freshman slots from today's 7,000 to 10,000, and to double the endowment to around $350 million by 2019.
Expansion may come easier on the half of the campus in growth-starved Philadelphia, by the cardinal's home.
"The cardinal's residence has been a passion of mine," Maguire said. In the early 2000s, he "pleaded with [then-Cardinal Anthony] Bevilacqua to sell the cardinal's residence." No deal.
Maguire was cochairman of an ambitious archdiocesan capital campaign when he received a call from Cardinal Justin Rigali, who was in Rome. "We're $16 million short," the cardinal told Maguire.
Maguire saw an opening. "I said, 'Your excellency, we'll give you $10 million [for the cardinal's residence], and I'll add the other $6 million on my own,' " Maguire recalled.
Rigali declined. "He said, 'Prayerfully consider giving me the $6 million,' " Maguire said, without the house. "I was so mad!" Maguire said, smiling.
Rigali's successor, Chaput, arrived last year ready to sell. Church negotiators hoped to raise $12 million, according to Maguire. St. Joseph's frugal interim administration - this was before Gillespie's arrival - had offered $8 million. Maguire agreed to add $2 million of his own, splitting the difference.
Contact Joseph N. DiStefano at 215-854-5194, JoeD@phillynews.com, or on Twitter @PhillyJoeD.