When musicians are young and haven't gotten in the habit of researching the pieces they play, one can get in the habit of assuming that whatever piece your teacher assigns you was natively written for your instrument. Why wouldn't you? Of course, sometimes there are exceptions to this rule, like if you play viola or tuba and nobody really wanted to write anything for your instrument...but for the most part, we assume what we play was written for us.
As a cellist, I still find myself re-discovering a piece I have heard many times before in its original context. Today...it was Dvorak's "Silent Woods". I had always thought it was a cello solo piece, but it turns out that it belongs to a larger collection of works for piano-four hand. I have always thought that description (four handed piano) was funny, since it makes me think of a piano with arms and hands sticking out of it like Hindu god, Shiva. Composers, however, wrote more works for piano-four hand than I had expected and most of them are underappreciated (Schubert, for example wrote many piano duet pieces).
The original source of this piece is Dvorak's From the Bohemian Forest for Piano-Four Hands, B. 133 (Op. 68) : V : Klid (Silent Woods). In the late 1800s it was common to take a popular piece and arrange it for other instrument pairings (you see that a lot today with pop songs showing up for string quartet/jazz ensemble/etc) and that's what Dvorak did. It is beyond serene and is worth listening to. Give the rest of the work a listen if you can find it, as well as Legends for Piano-Four Hands, B. 117 (Op. 59). They are beautiful works. Hope you enjoy.
Julian Thurber and Ingryd Thorson (piano)