One of the most popular repertoire, Minuet in G Major was thought to be written by J.S. Bach (1685-1750) for a long time, but it was originally composed by Christian Petzold (1677-1733). How do we know that? 

The Minuet is clearly in the collection book made by J.S. Bach, which is titled “Notebook for Anna Magdalena Bach” (1725). The book contains pieces written by J.S. Bach and some other composers, such as C.P.E. Bach, Francis Couperin etc. Since there was no indication of the composer’s name in the Minuet, scholars once concluded that it was Bach’s original piece. However, not long time ago from now, the manuscript of Petzolt’s harpsichord music collection (1729) was found in 1970, and the exactly same Minuet is included. This manuscript became the significant evidence to establish that the minuet was originally written by Petzold. Bach and Petzold had a good friendship, so there is no doubt that they had shared their music and inspired each other. 

Minuet in G Major by Christian Petzold, Tzschirich's manuscript (1729) - discovered in 1970.

Minuet in G Major by Petzolt is in the Notebook for Anna Magdalena Bach (1725).

The piano was invented by the Italian instrumental maker, Bartolomeo Cristofori (1655-1731). By 1700, he had completed his first keyboard instrument with the hammer action. The instrument was first named “gravicembalo col piano e forte” (harpsichord with soft and loud), and it still resembles a harpsichord through its shape, size, etc., but the mechanism is completely different. While the harpsichord produces sound by plucking the strings with plectra, the piano produces sound by striking the strings with the hammer. This hammer action can create more varieties of loudness and sensitivity, even just playing one single key.The name was shortened to “Fortepiano,” and now it commonly called “Piano.” The oldest surviving fortepiano by Cristofori (1720) is at the Metropolitan Museum of Art in New York. 

The oldest surviving forte piano made by Bartolomeo Cristofori (1720, Florence) — Metropolitan Museum of Art, New York City.