The Pope Marcellus Mass (Missa Papae Marcelli) was composed in honor of Pope Marcellus II, who reigned for only three weeks, in 1555; Palestrina is likely to have composed it in 1562, a couple of popes later. It is undoubtedly the most famous of Palestrina’s choral compositions, both for its undeniable beauty, and for a persistent legend which grew up around its composition. The Council of Trent (1545-63) was convened in response to the Protestant Reformation, to bolster church orthodoxy and eliminate internal abuses. The nature and uses of church music were an important topic of this council, especially of the third and closing sessions (1562-63). Two issues in particular concerned the participants: first, the utilization of music from objectionable sources, such as secular songs fitted with religious texts, and masses based upon songs with lyrics about drinking and sex; and second, the increasingly elaborate, complex polyphonic texture of the contemporary church music, popular with contemporary composers, which tended to obscure the words of the mass and sacred hymns, interfering with worshipers’ religious devotion. Some sterner members of the Council argued that only plainsong (a single line of music) should be allowed, and polyphony banned altogether. On September 10, 1562, the Council issued a Canon declaring that “nothing profane be intermingled [with] hymns and divine praises,” and banishing “all music that contains, whether in singing or in the organ playing, things that are lascivious or impure.”