Here's what Byron Katie says about why it's best to do the work on paper - particularly when starting out.
Because the mind is tricky. If you don’t write down your stressful thought, the mind will slip and slide around it. The mind is very clever. It will start defending its sacred concepts. It will qualify and justify and soon you won’t be able to give simple answers to the questions. The mind will outsmart you, so that it can keep all of its concepts intact.
But if you identify the stressful thought that you’re believing and put it on paper, there it is, in black and white. It’s stopped. It’s mind on paper. Your fearful mind never has been stopped before. It’s brought into the world and stabilized in the world—on paper. So, by putting mind on paper, you can put the four questions and the turnaround up against it.
When people do The Work, they need to notice when they begin to justify, defend, or go to a story. When you defend or justify, The Work stops working, because in that moment you’re no longer answering the questions. You’re doing what mankind always has done.
So, I invite people just to notice that and come back to The Work, and simply answer the questions. Be still, and take your time with each one of them. Your life depends on it. Your entire joyful life depends on it.