ABSTRACT
The development of the tonus peregrinus within the Western Church can effectively be described in terms of the theories of the German philologist Anton Baumstark. From combination of philological analysis, historiography and conjecture Baumstark drew the conclusion that at times of high devotion Christians have always returned to what they experience as traditional' and ancient'. Liturgical and musical differences between different regions have shaped the way in which the tonus peregrinus was treated polyphonically. There are, besides those discussed here, naturally polyphonic settings that have either been identified but only rudimentarily analysed, or not identified at all. Considering the number of works studied and occurrences of tonus peregrinus identified, it is unlikely that there are any works unaccounted for which could change the results much. Many out of the polyphonic applications of the tonus peregrinus which were scrutinized were initially answers to inherent voice-leading perceptible in the psalm-tone itself. Over time, composers occasionally departed from this artistic or circumstantial reasons.
