The importance of the mind in matters of health becomes clearer when we understand that what we commonly call our minds--the mental states which confront us day by day in our consciousness--are really but a small portion of our total mind. In addition to this conscious mind there is an enormous mass of our personality which is like a storehouse attached to our dwelling, a place to which we do not often go, but to which we can go in case of need. This storehouse is our memory, the things we know and can recall at will. And then there is another, still vaster storehouse--no one has ever measured or guessed the size of it--which apparently contains everything that we have ever known, perhaps also everything that our ancestors have known. A common simile for the human mind is that of an iceberg; a certain portion of it appears above the surface of the sea, but there is seven times as much of it floating out of sight under the water. This subconscious mind seems to be the portion most closely united with the body. It has its seat in the back parts of the brain, in the spinal cord and the greater nervous ganglia, such as the solar plexus. It is the portion of our mind which controls the activities of our body, all those miraculous things which went on before we first opened our eyes to the light, and which go on while we sleep, and never cease until we die. When we cut our finger and admit foreign germs to our blood, some mysterious power causes millions of our blood corpuscles to be rushed to this spot, to destroy and devour the invading enemy. We do not know how this is done, but it is an intelligent act, measured and precisely regulated, as much so as a railroad time-table. When the supply of nourishment in the body becomes low, something issues a notice by way of our stomach, which we call hunger; when we take food into the stomach, something pours out the gastric juice to digest it; when this digested food is prepared and taken up in the blood stream, something decides what portion of it shall be turned into muscle, what into brain cells, what into hair, what into finger nails. Sometimes, of course, mistakes are made and we have diseases. But for the most part all this infinitely intricate process goes on day and night without a hitch, and it is all the work of what we might call "the mind of the body."