Signs

And God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and years . . . Genesis 1:14


The musical score is full of signs. 

The note on the page requires a pretty complex bit of reading: 
its shape and coloration convey the duration of the sound while its location on the staff indicate the pitch to be performed.


And then we have an array of signs that indicate how to play a note or groups of notes.

These include:

articulations (how one note is connected or not connected to the next note)

phrases (which notes go together as a units)

dynamics (how loud or soft a note or group of notes should sound)

processes (changes in dynamics or pace over time).
  

What we lack is a sign for the specific purpose of delineating trajectory. 

All the other signs require interpretation so that we can understand the flow and direction of the music.

As Charles Rosen wrote in his book on the music of the Romantic generation, it is not enough to obey the signs. Interpretation - that is, our artistic duty - requires asking why those signs are there. Asking that question yields insight into the composer's strategy, insight into the composer's personal way of writing a sonata, a rondo, or whatever the form at hand is. 


In this way, we learn how the music is moving, and when we communicate that knowledge through our performances, the composer's personality and genius are heard and our listeners are moved, too.