Of the three processes for the purification of the nerves, described above, the first and the last are neither difficult nor dangerous. The more you practice the first one the calmer you will be. Just think of "Om," and you can practice even while you are sitting at your work. You will be all the better for it. Some day, if you practice hard, the Kundalini will be aroused. For those who practice once or twice a day, just a little calmness of the body and mind will come, and beautiful voice; only for those who can go on further with it will Kundalini be aroused, and the whole of nature will begin to change, and the book of knowledge will open. No more will you need to go to books for knowledge; your own mind will have become your book, containing infinite knowledge. I have already spoken of the Ida and Pingala currents, flowing through either side of the spinal column, and also of the Sushumna, the passage through the centre of the spinal cord. These three are present in every animal; whatever being has a spinal column has these three lines of action. But the Yogis claim that in an ordinary man the Sushumna is closed; its action is not evident while that of the other two is carrying power to different parts of the body.