I'd prefer not to act in the film I'm directing. I think, though, as an actor, you do learn how to turn things on and off quickly and kind of compartmentalize. You learn to accommodate the camera and the other actors, to notice where the boom is and where you mark is, and be able to repeat something a few times.
The invention of writing will produce forgetfulness in the minds of those who learn to use it, because they will not practice their memory. Their trust in writing, produced by external characters which are no part of themselves, will discourage the use of their own memory within them. You have invented an elixir not of memory, but of reminding; and you offer your pupils the appearance of wisdom, not true wisdom.