If the eye never sleeps all dreams will naturally cease. If the mind makes no discriminations, the ten thousand things are as they are, of single essence. These two eyes will have to sleep because they are part of the body and the body is not an eternal energy. It is a compound, it is not an elementary force. many things combine it. It is a mechanical device a bio mechanism. It depends on being fed continuous energy: food, water, air. Energy is created, fuel is created and the body runs - it is a mechanism. Your eyes will get tired because every machine gets tired.
You may be surprised to know that there has been a very great discovery in recent years that machines have to rest. Machines! you would never think it. Why machines? They don't need any rest. You drive a car for twenty hours, thirty hours the car needs a rest. You will be puzzled why? A car is not a mind. A car is not consciousness. Why rest? If everything is functioning is OK than you can go on and on, Just go on fuelling the car.
You are wrong. Now there are methods to judge when the car is tired. And the car is tired because every mechanism is bound to get tired, If you leave the car in the garage for a few hours, there are devices which will show when the car is ready to move again.
Every mechanism needs rest. Not only your body - every mechanism needs rest, than it revives again. Only consciousness needs no rest, because it is not a mechanism. it needs no fuel. It is perpetual energy, it is eternal energy, it is uncaused energy. It is there always.
That is why Sosan uses a singular word: if the eye never sleeps ....... otherwise he would say if the eyes. It is the third eye he is talking about. Even when your body sleeps, have you watched? - watch a little, you will be able to know something in you keep awake. Even while you are fast asleep, something, you may not be exactly clear what it is, But a point some where within you remains a witness.