Now it is here that we shall begin to profit by some knowledge about the invisible part of ourselves. The actual molecules of our body, as I have just said, are only so much dead matter. This inert material is pulled about in various directions by strings which we call muscles, according to the movements we wish our bodies to make, and these muscles are set in motion by the vibrations of the nerves.[4] But what is it that occasions these vibrations of the nerves? Here we begin to pass beyond the limits of official Science, though not beyond the limits of recognizable Law. We have to recognize the existence of an etheric body acting as an intermediary between intention, desire, or (in the case of human beings) thought of the soul and the physical vibrations of the nerves. This is why, in an earlier chapter, I have drawn attention to our power of sending out etheric vibrations beyond the limits of the physical body, as in the case of De Rocha's experiments. Such experiments show that there is in us something not composed of dense matter, which is able to convey vibrations to dense matter; and it is this something which we speak of as the etheric body. But if we wish to trace the links by which our thought operates upon the physical body, we find ourselves compelled to postulate yet another intermediary, what I have spoken of as the "Vital Soul"--a vehicle which does not _consciously think_, but in which what we may call race-consciousness becomes centred in the individual. This race-consciousness is none other than the ever-present "will-to-live" which is the basis of physical evolution--that automatically acting principle--which causes plants to turn towards the sun, animals to seek their proper food, and both animals and men to try instantly to escape from immediate danger. It is what we call instinct which does not reason. I may give a laughable experience of my own to illustrate the fact that conscious reason is not the method of this faculty. Once when on leave from India I was walking along a street in London in the heat of a summer's day and suddenly noticed just at my feet a long dark thing apparently wriggling across the white glare of the pavement. "Snake!" I exclaimed, and jumped aside for all I was worth, and the next moment was laughing at myself for not recollecting that cobras were not common objects in the London streets. But it looked just like one, and of course turned out to be nothing but a piece of rag. Well, instinct did its duty even if it did make a fool of me; but there is certainly no conscious reasoning in the matter, only the automatic action of inherent Law--"Self-preservation is the first law of Nature."