ABSTRACT
One of the most surprising appearances of the tonus peregrinus is in the requiem setting (K 626) of Wolfgang Amadeus Mozart. The appearance of the psalm-tone in a requiem Mass does not seem to pertain to any existing liturgical tradition, and we must try to trace this unexpected use partly from tendencies in contemporary works and partly from a theological context. A fascination with the tonus peregrinus has remained, over the last three hundred years, largely a personal affair for individual composers. In fact, the use of the tonus peregrinus is proportionately over-represented in the oeuvres of composers who primarily wrote for the chamber, stage and concert hall and never held an ecclesiastical position. There is evidence that the left-hand' group in the chart did not necessarily produce uninspired, routine music: settings such as those by Rheinberger or Dupr display no small degree of inspiration and originality.
