In the mineral kingdom the stone is dense; it does not know much. The reason is that it has little vacuum. The tree feels more than the stone because it has more vacuum, as the Indian scientist Jagarji Chandra Bose has pointed out. He tried to prove to the scientific world that trees breathe. Animals and birds show greater signs of life and a more pronounced knowing quality because the vacuum in them is greater still; and in man it is even more so. What makes one part of substance knowing and keeps another part without this faculty of knowing is the vacuum in one object and the denseness in another.