In the 18th century, just like today, Roman tourists gravitate toward the Vatican to view the famous Sistine Chapel and its ceiling by Michelangelo. But during Holy Week in the 18th century, there was an added attraction: performances by the Sistine Chapel Choir of a hauntingly beautiful piece of music, the a cappella setting of the Latin "Miserere" by the Italian composer Gregorio Allegri.

Over the decades since Allegri's death in 1652, elaborate vocal embellishments have been added to the original score. The Vatican jealously guarded these and Allegri's manuscript score as its exclusive property. Rumor had it—under threat of excommunication—that the choir was forbidden to let the score be taken out of the Chapel, copied, or even seen by any outsider.

On today's date in 1770, Wolfgang Mozart, age 14, was visiting Rome with his father. The Mozarts attended an evening service at the Vatican and heard Allegri's "Miserere." That same night—after just one hearing—young Wolfgang transcribed the piece from memory, and the Mozarts returned three days later to check Wolfgang's transcription against a repeat performance of Allegri's music. The elder Mozart thought that letting people know about this feat of memory might be "good PR" for young Wolfgang.

In any case, the Mozarts were NOT excommunicated, and Roman society WAS suitably impressed when they learned of the teenager's remarkable musical talent.