"I like it."  
"I don't like it." 
Just how central these pronouncements are in developing a sense of musical structure was again affirmed yesterday when a student began her playing of a Mozart sonata movement not at its beginning, but at the place which she likes best.  It put everything else in a meaningful perspective with shades of perceptible response in every note she played.  
I am deeply convinced that the art of composition consists of strategically locating such moments so that the player discovers them as if surprised by their vividness.  
A composer whose work I had recently reviewed commented on my having identified her obsession, which is harmony--not a particularly fashionable contemporary obsession.  I say double bravo to her that her structures make that audible to me, the listener.