Letting go of the data stream
This is the best analogy Campbell gives a beginner, and it dissolves a problem most people spend weeks stuck on.
You already know how to do this, he says. When you are absorbed in a good book you stop hearing the traffic outside. The sound is still arriving; you are simply not operating on it. Meditation, he says, is like that — except there is no story. It is just you, without a story, letting everything go.
So the instruction is not to block anything out. It is not that you do not know you have a body. It is that you stop operating on anything to do with the senses. The children next door are still audible. You just do not listen to them.
In his model this has a technical meaning. What you experience as physical reality is a data stream you are receiving and interpreting, and what meditation does is teach you to let go of it — you stop receiving the stream that defines this reality as the one you are in. Which he then reduces to one line: you intend to disconnect from this one, and that is called meditation.
Twenty minutes, which is his own number. He asks for that twice a day, and for three months of it before you form any opinion about whether it works.