We will take the first proposition, that intelligence and reason belong entirely to Nature, and not to the soul. The Vedânta says that the soul is in its essence Existence-Knowledge-Bliss; but we agree with the _Sânkhyas_ that all that they call intelligence is a compound. For instance, let us look at our perceptions. We remember that the _chitta_ (or the “mind-stuff”) is what is combining all these things, and upon which all these impressions are made, and from which reactions come. Suppose there is something outside. I see the blackboard. How does the knowledge come? The blackboard itself is unknown, I can never know it. It is what the German philosophers call the “thing in itself.” That blackboard, that “X,” is acting on my mind, and the _chitta_ reacts. The _chitta_ is like a lake; throw a stone upon it, and as soon as the stone strikes it a reactionary wave comes towards the stone. This wave is what you really know. And this wave is not like the stone at all, it is a wave. So that blackboard, “X,” is the stone which strikes the mind and the mind throws up a wave towards that object which strikes it, and this wave which is thrown towards it is what we call the blackboard. I see you. You as reality are unknown and unknowable. You are “X” and you act upon my mind, and the mind throws a wave towards the point from which the action came, and that wave is what I call Mr. or Mrs. So-and-So. There are two elements in this, one from inside and the other from outside, and the combination of these two, “X” plus mind, is our external universe. All knowledge is by reaction. In the case of a whale it has been determined by calculation how long after its tail is struck, its mind reacts upon the tail and the tail feels the pain. Take the case of the pearl oyster, in which the pearl is formed by the oyster throwing its own juice around the grain of sand that enters the shell and irritates him. There are two things which cause the pearl. First the oyster’s own juice, and second the blow from outside. So this table is “X” plus my mind. The very attempt to know it will be made by the mind; therefore the mind will give some of its own substance to enable it to understand, and when we understand it, it has become a compound thing,--“X” plus the mind. Similarly in internal perception; when we want to know ourselves. The real Self, which is within us, is also unknown and unknowable. Let us call it “Y.” When I want to know myself as Mr. So-and-So it is “Y” plus the mind. That “Y” strikes a blow on the mind, and when I want to know myself I must throw a blow upon the mind also. So our whole world is “X” plus mind (the external world), and “Y” plus mind (the internal world). We shall see later how this Advaitist idea can be demonstrated mathematically.