Introduction
A proviso

It is not easy to write about acting. Acting is an art, and art reveals the uniqueness of things. Talking about acting is therefore hard, because 'talking about' tends to make us generalise and generalisation conceals the uniqueness of things. All block, which we will discuss later, is both cause and result of generalisation. So writing about block is doubly dangerous. First we have to imagine a problem, and then struggle to suggest solutions for this vagueness that are as specific as possible — for you can never be too specific. These generalisations may not be true, but they have proved useful.