We do not know anything about our own bodies; we cannot know. At best we can take a dead body, and cut it in pieces, and there are some who can take a live animal and cut it in pieces in order to see what is inside the body. Still, that has nothing to do with our own bodies. We know very little about them. Why do we not? Because our attention is not discriminating enough to catch the very fine movements that are going on within. We can know of them only when the mind becomes more subtle and enters, as it were, deeper into the body. To get the subtle perception we have to begin with the grosser perceptions. We have to get hold of that which is setting the whole engine in motion. That is the Prana, the most obvious manifestation of which is the breath. Then, along with the breath, we shall slowly enter the body, which will enable us to find out about the subtle forces, the nerve currents that are moving all over the body. As soon as we perceive and learn to feel them, we shall begin to get control over them, and over the body. The mind is also set in motion: by these different nerve currents, so at last we shall reach the state of perfect control over the body and the mind, making both our servants. Knowledge is power. We have to get this power. So we must begin at the beginning, with Pranayama, restraining the Prana. This Pranayama is a long subject, and will take several lessons to illustrate it thoroughly. We shall take it part by part.