John Weeks Moore, Complete Encyclopaedia of Music… (1880)
“ Of all his works, the "Miserere" is the most distinguished. It was, for upwards of a hundred and fifty years, annually performed in passion week, at the pope's chapel, on Wednesday and Good Friday; it is in appearance so simple as to make those who have only seen it on paper wonder whence its beauty and effect could arise ; but it owes its reputation more to the manner in which it is performed than to the composition ; the same music is many times repeated to different words, and the singers have, by tradition, certain customs, expressions, and graces of convention, which produce great effects ”
