That music survives from the past with the inevitable loss of its original context is a truism that might be challenged above all by sacred music, on the grounds that a liturgy provides a timeless context within which music composed for its service can continue to fulfill its original purpose. Indeed, the Catholic liturgy that emerged from the Counter-Reformation after the Council of Trent (1545–63) – the Tridentine Rite, a normative form of late medieval Roman Use – persisted until the reforms of the Second Vatican Council (1962–65), providing for four centuries a constant framework of worship (local variations and emphases of practice aside) for which music could long remain in use. As many a set of manuscript parts from the repertories of religious establishments in the former Habsburg lands of central and eastern Europe attests, Haydn's sacred music continued to be performed within the Catholic liturgy throughout the nineteenth century, a tradition often reflected in the nature of the performing material (a core of original eighteenth-century parts, supplemented by various accretions) and the recording of dates of performance on the reverse of the organ part or folder. Yet today Haydn's sacred music is seen to have suffered a loss of context more far-reaching than that undergone by some other genres of his output. The late masses for instance – works large enough to form independent musical entities – are performed as concert pieces, crossing boundaries of genre, style, and purpose between “church” and “chamber” more fundamental than the contextual changes affecting, say, the string quartets and symphonies.