On this August Sunday, the members at St. Francis were packed in — few vaccinated or wearing masks. In the choir loft, Kwasniewski, Bauer and others were chanting Gregorian melodies, projecting a warbly sound that echoed as if the church were a stone cave. At the altar, Heffernan was leading the Mass ad orientem — facing toward the altar, back turned to the congregants — and praying in Latin, sometimes barely above a whisper. For congregants, the Mass had the feel of mystical theater. They were witnessing something that was hard to understand, and it was up to them to find the meaning, to pray silently to God.