2.14Let's apply that to a melody

Suppose the melody note is E.

In C major, which native chords contain E?

C:

C E G

Em:

E G B

Am:

A C E

Therefore E can naturally sit over:

C, Em, or Am

These correspond to:

I, iii, vi

Now suppose melody note is F.

Which chords contain F?

Dm:

D F A

F:

F A C

B°:

B D F

So:

ii, IV, vii°

This is exactly the logic we'll use when harmonizing melodies later.