Rhythm Is Hard

Rhythm is one of the most difficult aspects of music to teach and to learn. Excellent rhythm is what separates the best musicians from mediocre.

What is good rhythm?

Good rhythm is hard to describe but when you hear it and feel it you know what it is.

It don't mean a thing if it ain't got that swing

— Irving Mills

What is the quality of movement that makes Gene Kelly so fun to watch? (Gene Kelly also embodies all the 5 principles except maybe the one about the hands.)