But over the last 14 years, Gillis, a retired Haverford College classics professor who was raised Catholic, has amassed an arsenal of books on the topic.
The 2,500 volumes mainly cover the Holocaust, with subjects ranging from Jewish resistance during the war to the prosecution of Nazi criminals in its aftermath.
A compilation of fiction, non-fiction, memoirs and illustrated histories, the works also offer resources on European Jewry before Hitler's rise.
On Monday morning, Drexel University incorporated roughly 900 of these titles into its W.W. Hagerty Library, located at 33rd and Market streets.
Two hundred more items from the collection will soon reside at Akiba Hebrew Academy; the remaining 1,400 are already in circulation in the library system shared among Haverford, Bryn Mawr and Swarthmore colleges.
Drexel's dedication featured comments by Gillis, as well as by friends Stanley and Helen Segall, for whom the collection is named. Stanley, an expert on nutrition, worked at Drexel for almost 40 years; his wife, Helen, a Holocaust survivor, taught Russian at Dickinson College.
Addressing those at the event, Alison Lewis, a reference librarian who's acted as point-person on the project, praised the quality of Gillis' volumes.
"Usually when libraries receive donations, it's kind of a mixed blessing — [the items] are either not in the best condition or not exactly what you're collecting," she explained.
But "these are the best books by the best authors from the best presses, and they're almost 100 percent in pristine condition."
Lewis said that the titles will be integrated into the library's second floor, shelved under categories like arts, literature, women's studies and politics.
Still, noted the speaker, each copy will contain a commemorative nameplate, and will be searchable by the collection name.
The gift comes at an opportune time for the university, which has been working in recent years to bolster its reputation in the humanities.
During the dedication, arts and sciences dean Donna Murasko publically thanked Gillis for contributing to this effort.
The donation reaffirms that "Judaic studies is alive and well and growing," said the dean, referring to the 9-year-old program.
Indeed, this was an important consideration for Gillis, who stressed that he "wanted to help plant a seed for research."
The scholar added that he had yet another reason for choosing Drexel: He'd been friends with the Segalls for over 30 years.
In fact, each of the donor's gifts recognizes survivors who have touched his life. Frank Steinberg — the Akiba honoree — worked at Gillis' alma mater, Massachusetts Institute of Technology, while Else Goldberger — for whom the tricollege collection is named — was a Haverford librarian.
"My life was shaped by refugee people," explained Gillis. And this way of commemorating them "is so much better than a memorial.