Let's say that you have a big important idea you want to share with the world.
Could you do it in less than a page?
Less that two hundred fifty words?
Less than one hundred words?
A paragraph? (Of less than a hundred words, OK?)
Could you get it down to one hundred forty characters, a la Twitter?
I sometimes think of Twitter as a spiritual practice, in that it forces me to find the core and discard what is not absolutely needed.
Granted, sometimes issues require more than 140 characters.
But if you can keep it under a page, you've got a better chance of people sticking around to read/hear your message. (And you have a better chance of remembering it. Both because it's shorter and because you've spent some time honing it.)