We come next to the other aspect of philosophy. There are Buddhists who deny the whole theory of the soul that I have just now been propounding. "What use is there," says the Buddhist, "to assume something as the substratum, as the background of this body and mind? Why may we not allow thoughts to run on? Why admit a third substance beyond this organism, composed of mind and body, a third substance called the soul? What is its use? Is not this organism sufficient to explain itself? Why take anew a third something?" These arguments are very powerful. This reasoning is very strong. So far as outside research goes, we see that this organism is a sufficient explanation of itself — at least, many of us see it in that light. Why then need there be a soul as substratum, as a something which is neither mind nor body but stands as a background for both mind and body? Let there be only mind and body. Body is the name of a stream of matter continuously changing. Mind is the name of a stream of consciousness or thought continuously changing. What produces the apparent unity between these two? This unity does not really exist, let us say. Take, for instance, a lighted torch, and whirl it rapidly before you. You see a circle of fire. The circle does not really exist, but because the torch is continually moving, it leaves the appearance of a circle.