Before looking at the Synod of Pistoia, let's define Archaeologism (also called antiquarianism.)  Unam Sanctam defines it: Archaeologism is not so much a heresy as a fad, a certain approach to Catholic liturgy and practice. Its distinguishing characteristic is an excessive value placed on those Catholic practices which came earlier in historical-chronological succession. For the archaeologist, first is always best. A practice or prayer of the patristic Church is “better” or “purer” than a practice of the medieval Church. Consequently, the goal of any true liturgical renewal ought to be to return to the practice of the first Christians, inasmuch as possible. The modern Church ought to imitate the apostolic [...]