[how] + [very] -- sonata form
Sonata form is a workhorse of classical music. Its enduring appeal comes from how its different themes interact with its harmonic structure.
A sonata has two main motifs — a masculine (M) and a feminine (F). The masculine begins the piece in the tonic (T). Eventually, the feminine appears in the dominant (D). After some roving developmental material, we hear the masculine theme in the tonic again. But this time, the feminine theme that follows remains in the tonic to close things out.
This produces two overlapping levels of structure displaying two very different types of reduplication.
MFMF
TDTT
The first doubles the entire MF unit to produce (MF)(MF). The second reduplicates the final T to give TD(T)(T). This repetition of the tonic is essential for reasserting the key center, but the fact that it now occurs with the F theme supplies the necessary variety.