One thing that keeps getting my attention is whether by conscious choice or by intention, they all have in common their use of an internal pattern: Chopin's mazurkas, Shapespeare's sonnets and Michelangelo's triangles. Something about that structure enables artists to express the impact of a moment in time and make it eternal.
What's exciting to me is not the pattern itself, but how the the artists transform their pattern of choice while retaining it's underlying formation.
And so discovering patterns and finding ways artists transform them is what I'll be exploring as I resume my Compose tutorials. That should keep me busy for a while!