How can one wipe out all the innumerable pictures which hinder one? The whole process of the Sufi method is this: to make the photographic plate of the mind clear. This can be done by the practice of concentration. The horses in the forest will not come if you call them to come to you, nor will they walk as you wish them to walk, because they are untrained horses. So are one's thoughts and imaginations; they go about in the mind without harness, without rein. And when this is taken in hand, then it is just like the trainer of a circus who tells the horse to come, and the horse comes, and then he tells the horse to go, and the horse goes; he tells the horse to run, and the horse runs; to stop, and the horse stops. Working with thoughts is just like what the circus-man does.