An example from Johann Sebastian Bach's Well Tempered Clavier, also known as the 48 Preludes and Fugues, this prelude's form and construction is obvious yet it is a delight to both listen to and play. This particular prelude in F minor was borrowed by Jem for her song called "They" (and then sampled by others including Glee) but many years before this a vocal version was performed by the Swingle Singers - here they are performing this prelude on YouTube. The prelude is in the key of F minor and, together with its fugue sibling, it is catalogued as BWV 881.
Although there are some easier preludes and fugues in the set, much of Bach's Well-Tempered Clavier is quite challenging to play. However the complete set has for a long time been considered a must for any serious student of piano. Some other preludes and fugues from the set are available on mfiles if you check the Bach page or Classical Sheet Music page. If you have aspirations to be a good classical pianist then we recommend getting the complete Well-Tempered Clavier which comes in two books. Here are links on "sheet music plus" to Book 1 and Book 2 of the Well-Tempered Clavier.
The audio controls below allow you to play the mp3 version of Prelude No.12 in F minor from Book 2 or you can download the MP3 file. You can also download the midi version of Prelude No.12 in F minor from Book 2 or alternatively edit/play the midi file.
The image below is the first page of the sheet music, and here you can download the full sheet music for Bach's Prelude No.12 from book 2 in PDF format.