Aida on a Harley

Plus a few other interesting flourishes.

But I wonder what it is about the perfect fourth! From Wikibooks: "The perfect fourth is the inversion of the perfect fifth. In common practice music, it can be both consonant and dissonant: in this case, it has a need for resolution when unsupported by lower notes, in which case it is dissonant even though it sounds as "good" as the fifth. The fourth is always consonant when supported by a lower third or perfect fifth, for example, E-G-C-E is consonant, but G-C-E is dissonant. In more contemporary music, many consider the fourth to always be as consonant as the fifth."

It's fascinating to me. It sounds majestic and marchful. (I made up that word!) Where else do we find it? Aha!  Here's a list of songs for interval recognition,  including the perfect fourth.

Hmm, not always so marchful. But interesting.