the case of sensible qualities which appear to be at a great distance from us. When, for instance, (as we say), "we see the moon," _what_ we perceive (if the moon be full) is a round bright silver disc, of a small size, at a place very distant from us. Does that silver disc exist at that place? With what suppositions does the assumption that it _does_ conflict? Only, so far as I can see, with the supposition that the place in question is _really_ occupied by a body such as science has taught us to suppose that the moon _really_ is--a spherical body immensely larger than objects, in comparison with which the silver disc which we perceive is small; _or else_ with the supposition that the place in question is really occupied by some part of our atmosphere, or some part of the medium which science supposes to exist between our atmosphere and the moon; _or else_ with the supposition that the place in question is really occupied by what we might see, if the moon were nearer to us by many thousands of miles. Unless we suppose that some other object _is_ in the place, in which the silver disc appears to be, and that this object is of a kind which cannot occupy the _same_ place which is occupied by a silver disc, we have no reason to suppose that the silver disc does _not_ really exist in the place where it appears to be. And, in this case, we _perhaps_ have reason for both suppositions and should therefore conclude that the silver disc, which we perceive, does not exist in any real place.