I've discovered the Secret...

Yep - that's essentially the definition of "functional harmony"

Ya but it's more than just the harmonic side of it. It's the tempo and the volume changes that also create the tension and resolution.

Think about it...

If there is a really loud intense section of a song and then it stops and there is silence... that creates resolution. But if the silence continues it creates tension again.

So silence creates both resolution and tension in just a few seconds. Interesting eh?

Yes - and patterns... repeating a sequence over and over builds tension; varying the last repetition provides release. And range... playing in the very low or high registers creates some tension. And accents. And long notes - which can be tension or release. And 'blue notes' for tension, with chord tones for release. And ornaments like trills. And timbre - for guitarists, things like pinch harmonics or effects (or think of how a raspy sax attack creates tension, and that smooth tone at the end of a phrase releases it).

So yeah, in a nutshell it's just tension and release. That's how we make music tell our stories :)

Harmony in itself is pretty powerful. I think the right notes over the right chords make it all come together. We could cite example after example. Probably the keystone of popular music.