Attempts to explain what is meant usually get bogged down after just a few paragraphs.
So how about explaining the idea using examples?
Great idea, but really telling, convincing examples can be hard to find.
Here's one that I find convincing:
Now listen. I vary the sentence length, and I create music. Music. The writing sings. It has a pleasant rhythm, a lilt, a harmony. I use short sentences. And I use sentences of medium length. And sometimes, when I am certain the reader is rested, I will engage him with a sentence of considerable length, a sentence that burns with energy and builds with all the impetus of a crescendo, the roll of the drums, the crash of the cymbals–sounds that say listen to this, it is important.
Source: GoodReads by Gary Provost
To hear it read with aplomb, try this.
It looks and reads better with a layout that I can't readily equal using Blogger:
For information on Gary Provost (1944-1995), see here.