Modern physiology says that between the two eyebrows is the gland that is the most mysterious part of the body. This gland, called the pineal gland, is the Shivnetra, the eye of the Shiva, of tantra. Between the two eyes there exists a third eye, but it is non-functioning. You have to do something to open it. Otherwise, it remains closed.
Close your eyes and focus both eyes on space in the middle of your eyebrows. Give total attention to it. This is one of the simplest methods of being attentive. You cannot be attentive to any other part of the body so easily. This gland absorbs attention like anything. If you give attention to it, both your eyes become hypnotised with the third eye. They become fixed; they cannot move. The third eye forces attention. It is magnetic. Your attention is brought to it forcibly. It is absorbed.
It is said in ancient tantra scriptures that for the third eye, attention is food. And once you feel that the gland itself is magnetically pulling your attention, it is not so difficult. For the first time you will see thoughts running before you. You will become the witness. It is just like a film screen: thoughts are running and you are a witness.