Does It Go Up or Does It Go Down?

The answer most of the time is it goes sideways, i.e., from left to right as on the printed page or on the piano.  The only  time "it" truly goes up or down is when singing.

Playing the Bach Two-Part Inventions as if they are puzzles about how many ways an instrumentalist can disguise upward or downward motion utterly transforms them.  I looked up Inventions in Grove yesterday where, according to John Caldwell, they are "textless ricercare,"  a description I quite enjoy.  In other words, they are textless instrumental works searching for the sense of text, which in Baroque terms would have had a great deal to do with up and down.

The Three-Part are not called Inventions but Sinfonias. As I do not (yet) have three hands I always find these works challenging.  But I am working on it.