One of the earliest acts of the new pontificate was to forbid the use in the services of the Church of any music later than Palestrina, a drastic order justified by the extreme degradation into which church music had fallen in Italy, but in general honoured rather in the spirit than in the letter.
Mozart imports from church music 3 trombones for special passages in his operas.
With modern orchestral conditions the text seems positively to demand an unecclesiastical, not to say sensational, style, and probably the only instrumental Requiem Masses which can be said to be great church music are the sublime unfinished work of Mozart (the antecedents of which would be a very interesting subject) and the two beautiful works by Cherubini.
In 1774 he published two volumes De cantu et musica sacra; in 1 777, Monumenta veteris liturgiae Alemannicae; and in 1784, in three volumes, Scriptores ecclesiastici de musica sacra, a collection of the principal writers on church music from the 3rd century till the invention of printing.
Symphony and popular concerts are held throughout the year in various public halls, and, during the winter, concerts of church music are frequently given in the Protestant Kreuzand Frauen-Kirchen, and on Sundays in the Roman Catholic church.
He established and richly endowed the first foundling hospital, built and repaired numerous churches, constructed the Sistine Chapel and the Sistine Bridge, improved church music and instituted the famous Sistine choir, commissioned paintings on the largest scale, pensioned men of learning, and, above all, immortalized himself as the second founder of the Vatican library.