Relationship of primary triads to secondary triads

From Paul Erlich:

> I once mistook the II triad in first inversion for an IV triad, the only
> mistake I ever made in Roman numeral dictation in my college ear-training
> class. To me, that's sure evidence of a commonality in function.

No doubt about it!!! LOL

Kind of shows the importance (NOT) of Roman numeral references.

Jerry