In plain words
That is enough. Nothing more is needed. The bad habit of standing about at the house and in the bazaar and talking is very bad indeed. If you need anything, you can discuss it after you go back to the hostel, to your room. No young person should talk while going about house and bazaar. You must keep your gaze under control. We are human beings. We are not crows. Crows do not stay still even for a minute; this way and that they go. So only when we follow discipline of this kind do we become those who have attained true humanness.
For students this is most essential. When studying, we must sit in the right posture and study. For this body has a special distinction. Cattle and beasts have a spinal column that is bent. Man has a spinal column that is straight. The path that runs from the mūlādhāra to the sahasrāra must stay straight. When it is in the right position, it goes on giving right thoughts. If instead it bends, it does not follow an orderly course. In every human being there are 101 nāḍīs. Of them, only one nāḍī is special. It is joined solely with the sahasrāra. It is a help to those on the spiritual path who are set firm in dhyāna. This is what they called the suṣumnā nāḍī. Only when, in the working of the iḍā, piṅgalā and suṣumnā nāḍīs, they meet from the point between the eyebrows, does this suṣumnā nāḍī give a special one-pointedness. In the spinal column there are 33 rings in all. It is in those from the ninth to the twelfth that the suṣumnā nāḍī shines out brightly. As a flash of lightning between black clouds shines so brilliantly, in just the same way a streak of lightning flashes for an instant in our spinal column, they say. That is the very support of our life. Those who practise kuṇḍalinī yoga understand this properly. Do any yoga, or do no yoga at all, you must keep the body in the right posture. They lie face down. They put their books on the pillow. Then they bend themselves over. However many hours such people study, nothing goes into their heads.