Lassus was probably the most prolific composer of all time, having left the enormous number of nearly 2,500 separate compositions. As his master, Duke Albert, was a staunch and devout Catholic, by far the larger part of his creative energy was expended in the field of pure church-music, of which he wrote no less than 1,200 motets and _sacræ cantiones_, 51 masses, about 180 Magnificats, and over 150 lamentations, psalms, hymns, Requiems, Ave Marias, antiphons, etc. The most celebrated of his works and, according to Ambros,[28] the only other work of the sixteenth century worthy to stand beside Palestrina’s _Missa Papæ Marcelli_, are the ‘Penitential Psalms,’ which were composed at the duke’s suggestion prior to 1565, though not published until 1584. The establishment of the date of their composition definitely upsets the familiar legend that they were written for Charles IX of France to solace his troubled conscience after the horrors of the massacre of St. Bartholomew. It may well be, however, that they were sung before this unhappy monarch, for Lassus spent some time at the court of France at Charles’ invitation. Lassus’ masterpiece, though written comparatively early in his career, possesses in a marked degree all the qualities of strength, grandeur, dignity, repose, and especially impersonality and absence of what would now be called dramatic effects, that are the distinguishing characteristics of the maturest period of ritual-music of the great Netherlander and his Italian compeer, Palestrina. The ‘Penitential Psalms’ (the 6th, 32d, 38th, 51st, 102d, 130th, and 143d) were set for from two to six voices, according to the suggestion of the text, and the style of expression varies from the extreme simplicity of the opening chords to the massive and intricate tone-structures by means of which he depicts the remorse and fear of the penitent sinner. But, while a note of sorrow and wailing runs throughout, the master has with equal genius portrayed the strong consolation of sincere repentance and the sure hope of pardon from a loving God.