our way of communication, are indirect and inferential. They must make the circuit, and must use the symbol, of bodily change. If a common ruler of souls could give to any one a message from the inside, such a message could never be handed on but by alterations of bodies. That real identity of ideal content, by which all souls live and move, cannot work in common save by the path of external appearance.
And, with this, we are led to the question of the identity between souls. We have just seen that immediate experiences are separate, and there is probably no one who would desire to advocate a contrary opinion. But there are those, I presume, who will deny the possibility of two souls being, in any respect, really the same. And we must endeavour very briefly to clear our ideas on this matter.
It would be, of course, absurd to argue that two persons are not two but only one, or that, in general, differences are not different, but simply the same; and any such contention would be, doubtless, a wilful paradox. But the principle of what we may call the Identity of Indiscernibles, has quite another meaning. It implies that sameness can exist together with difference, or that what is the same is still the same, however much in other ways it differs. I shall soon attempt to define this principle more clearly, but what I would insist on, first, is that to deny it is to affront common sense. It is, in fact, to use words which could have no meaning. For every process of psychical Association is based on this ground; and, to come to what is plainer, every movement of our intellect rests wholly upon it. If you will not assume that identity holds throughout different contexts, you cannot advance one single step in apprehending the world. There will be neither change nor endurance, and still less, motion
