superior sentences

From John Leonard's introduction to Joan Didion's collected non-fiction, We tell ourselves stories in order to live:

"I have been trying forever to figure out why her sentences are better than mine of yours...something about cadence. They come at you, if not from ambush, then in gnomic haikus, icepick laser beams, or waves. Even the space on the page around these sentences is more interesting than it ought to be, as if to square a sandbox for a Sphinx."