Asides plug in material not directly related
to the main idea. Parentheticals can also make it easier for readers to
make the leap from subject and predicate or to navigate the elements of
a series..
Cheering supporters waved little Union Jacks (provided
by Blair's ever assiduous campaign staff) and shouted "Tony!
Tony!"
What moves this comment about Blair's staff to
an aside? Parentheses. Mere commas would have signaled the reader
that the parenthetical material was simply adding a bit of dispensable
detail.
Sterling's sci-fi protagonist goes through an implausible
procedure (albeit one based on an extrapolation of some real
medical research) that restores her youth; who would not give
most of their worldly goods for that?
She also deserves commendation for teaching (for
better or for worse) the male publishing establishment a thing
or two about how to sell a book.
After all, action movies, with minimal subtitles,
cross linguistic barriers more easily than dramas built on dialogue
and nuance. (Boys with toys travel well, the saying goes.)
Sometimes an entire sentence is a parenthetical
aside.