A block is when we can't get through to the real thing. Many writers write a great deal, but very few write more than a very little of the real thing. So most writing must be displaced activity. When cockerels confront each other and daren't fight, they busily start pecking imaginary grains off to the side. That's displaced activity. Much of what we do is a bit like that, I fancy. But it's hard to know which is which.