12.1Start from the familiar dominant

In C major:

G7 → C

G7 is the normal dominant of C.

Roman numerals:

V7 → I

Nothing unusual yet.

Now suppose we want to make Am sound like a temporary destination.

What is the dominant of A?

E.

So:

E7 → Am

Even though E7 contains G♯, which is not in C major, it works beautifully because it creates a strong pull toward Am.

This is called:

V7/vi

Read:

“five-seven of six”

because Am is vi in C major.