The Fantasia in G major, catalogued as BWV 572 or BC. J82, is a work for organ by German composer Johann Sebastian Bach. Though it is not accompanied by a Fugue, it has three main moments or sections (allegro, grave, and lento). As with most of the music written by bach before 1723, it survives thanks to his pupils' transcriptions. It is generally agreed that it was written during his Weimar period. In this piece Bach renounced the tradition of writing organ capable of being played in a harspichord.
