Liszt drew inspiration for his composition À la Chapelle Sixtine from two contrasting motets he had heard in the Sistine Chapel: Gregorio Allegri's famous Miserere mei deus and Mozart's Ave verum corpus, the composer's last work of this genre. From Allegri's work, Liszt adopted the characteristic harmonies and, based on them, created a passacaglia in G minor, whose variations build to a dramatic climax. Only then does Mozart's motet appear in a simple transcription in B major. Through artful modulations, the variations return in abbreviated form before Liszt presents Mozart's Ave verum corpus again, this time in F-sharp major—a section that Tchaikovsky later used for his orchestral suite "Mozartiana." Liszt expands Mozart's music, allows for a gentle modulation to G major, and concludes the work with distant allusions to Allegri in the bass.
