Actually I intentionally skipped a lot of steps in interest of clairity, at sacrifice of detail. This is what I was generalizing when I said "The simple 'connect the dots' shape contains frequencies higher than the Nyquist frequency. Or we could say the D/A step produced these frequencies, however we want to look at it. In any case, they will be removed in the next step."
Not technically complete, but I know how much I hate it when I ask a question and get an overly detailed answer to a question. It's hard to know where to draw the line.
One item that is also very often ignored or forgotten is the low pass before the sampling step.