1.17Another crucial interval: the fifth

Play:

C + G

Then:

D + A

Then:

E + B

Then:

F + C

Notice how stable/open they sound.

The fifth doesn't tell you major or minor.

Compare:

C-G

It could belong to:

C major

or:

C minor.

Only when you introduce:

E

or:

E♭

does the identity become clear.

This becomes useful later when creating bass accompaniment.