The mind is a scattered thing. It concerns itself with thousands of different items at once. Things you see around you. Things you hear and smell. Things you think about. Things you try not to think about. You must learn to concentrate such that you can visualize at will one item, one item only, and nothing else. If you work hard, you may be able to concentrate your conscious mind on any one object you select for around three and one-half minutes. This will take about 20 years of diligent, daily effort. "Twenty years!" I cried. Twenty years. It may take longer. That's the usual time, if you are able to do it at all. I'll be an old man by then! The time varies. Some take ten years, some take thirty. On extremely rare occasions, a special person comes along who's able to develop the power in only one or two years, but this is one in a billion. Not you. Is it that difficult to concentrate the mind-- Almost impossible. Try it and see. Shut your eyes and think of something. Think of just one object. Visualize it. See it before you. In a few seconds, your mind will wander. Other thoughts will creep in. It's a very difficult thing. Thus spoke the great, wise, old yogi.