Caprice number 30 reminds me of J.S. Bach's Sheep May Safely Graze. I think it's because of the pulsing harmony, present in the dotted sixteenth notes. And just like the Bach, this caprice moves along in rhythm while still projecting a harmonic sense of calm.
It wasn't all calm in my head when I was performing this however - there were a few nervous spots, the most notable one being at measure 18, where one is supposed to sound placid while hitting a fingered tenth on the viola. And since my viola is 16 3/8 inches and I'm only 5'6 (albeit with long arms), this was not an easy ask. Listening objectively, I would have lingered longer on that dissonant tenth, which is part of a beautiful chord progression. But physically I didn't feel like I could without risking intonation!
Another spot to watch out for: the long double-stop passage from mm. 25-32. It gets going in measure 29, and you'd better have your muscle memory in place, even if you're using music.
But overall, I love this caprice. Another beautiful aria for the viola!