Chapter VI Sloka13

sm< kayizrae¢Ivlt; xaryÚcllt; iSwr>,
s<àeúy naiska¢< Sv< idzíanvlaekyn!.

samaÕ k˜yaþirogreevaÕ 
dh˜rayannacalaÕ sthira× |
samprekÿya n˜sik˜graÕ svaÕ 
diþaþc˜navalokayan ( 6|13)||

Let him firmly hold his body, head and neck erect and still, gazing at the tip of his nose, without looking around.
Commentary: The Lord describes here the pose of Asana and the Drishti (gaze) in this verse.
You cannot practise meditation without a firm seat. If the body is unsteady, the mind will also become unsteady. There is an intimate connection between the body and the mind.
You should not shake the body even a bit. You should attain mastery over the Asana (Asana-Jaya) by daily practice. You should be as firm as a statue or a rock. If you keep the body, head and neck erect, the spinal cord also will be erect and the Kundalini will rise up steadily through the subtle 'nerve-channel' (Nadi) called the Sushumna. Sit in the 'lotus pose' or the 'adeptpose'. This will help you in maintaining the nervous equilibrium and mental poise. You should steadily direct you gaze towards the tip of your nose. This is known as the Nasikagra Drishti. The other gaze is the Bhrumadhya Drishti or gazing between the two eyebrows where the psychic centre known as the Ajna Chakra is situated. This is described in chapter V, verse 27. In Bhrumadhya Drishti direct the gaze towards the Ajna Chakra with closed eyes. If you practise this with open eyes, it may produce headache. Foreign particles or dust may fall into the eyes. There may be distraction of the mind also. Do not strain the eyes. Practise gently. When you practise concentration at the tip of the nose you will experience Divya-Gandha (various aromas). When you concentrate your gaze at the Ajna Chakra you will experience Divya-Jyotis (perception of supra-phenomenal lights). This is an experience to give you encouragement, push you up in the spiritual path and convince you of the existence of transcendental or supra-physical things. Do not stop your Sadhana. Yogins and those Bhaktas who meditate on Lord Siva concentrate on the Ajna Chaktra with the Bhrumadhya Drishti. You can select whichever Drishti suits you best.
Though the gaze is directed towards the tip of the nose when the eyes are half-closed and the eyeballs are steady the mind should be fixed only on the Self. Therefore you will have to gaze, as it were, at the tip of the nose. In chapter VI, verse 25, the Lord says: 'Having made the mind abide in the Self, let him not think of anything'. Gazing at the tip of the nose will soon bring about concentration of the mind.
Whichever be the point select, visualise your own tutelary deity there and feel His Living Presence.