Robert Estrin: Why Perfect Intervals are Perfect: Unlock the Key! - From the Music Expert

https://www.virtualsheetmusic.com/experts/robert/why-perfect-intervals-are-perf/ - Why are some musical intervals labeled "major" while others are called "perfect"? It sounds like arbitrary music theory snobbery, but there is actually a brilliant mathematical rule behind it. In this video, Robert Estrin cracks open the concept of interval inversion to show you the hidden symmetry of the musical staff—and shares the ultimate cheat code for identifying intervals instantly.