I got it.
And I raised my hand and said (hee hee!), "So if you want to explore just the questions that interest you, choose your own contrasts and deal with the overlap. But if you want to explain all the variance, choose an orthogonal set of contrasts and deal with the complex contrasts."
And the prof smiled and gave me a big thumbs up and went on with the lecture.
And I sat back in my seat with a huge satisfied grin on my face because - FINALLY! - something about some of the choices we might make about what statistical procedures to use when made sense to me.
Awesome. And by "awesome" I mean, "Mwahahahahahahahaaa!" :) :)