fy the argument, that stimuli from without giveIf any image-centre really exists, it is likely to be a kind of keyboard, played upon by memories, as the sense-organ is played upon by a objects. birth, either in the cortex or in other cerebral centres, to elementary sensations. In fact, every perception includes a considerable number of such sensations, all co-existing and arranged in a determined order. Whence comes this order, and what ensures this co-existence? In the case of a present material object, there is no doubt as to the answer: order and co-existence come from an organ of sense, receiving the impression of an external object. This organ is constructed precisely with a view to allowing a plurality of simultaneous excitants to impress it in a certain order and in a certain way, by distributing themselves, all at one time, over selected portions of its surface. It is like an immense keyboard, on which the external object executes at once its harmony of a thousand notes, thus calling forth in a definite order, and at a single moment, a great multitude of elementary sensations corresponding to all the points of the sensory centre that are concerned. Now, suppress the external object or the organ of sense, or both: the same elementary sensations may be excited, for the same strings are there, ready to vibrate in the same way; but where is the keyboard which permits thousands of them to be struck at once, and so many single notes to unite in one accord? In our opinion the 'region of images,' if it exists, can only be a keyboard of this nature. Certainly it is in no way incon-
