Question

Since absolute forms such as the symphony and the concerto generally have no program, in your opinion, what gives them their sense of shape and meaning?

Answer 1

The sonata form of each movement and the relationship between movements gives the composition its shape. The meaning, if any, is contained in the music itself.

Answer 2

I recommend this website for further reading:
http://everything2.com/e2node/Sonata%2520form