of the corporeal part of the process;--and it is likely to continue so forever,--at least in all the more important respects of our ignorance,--since any changes which occur in the corpuscular motion, and consequent new arrangement of the particles of the substance of the brain and nerves, corresponding with the diversities of feeling during those particular states,--if such corpuscular motions or changes do really take place,--are probably far too minute to be observable by our organs; even though we could lay open all the internal parts of the brain to complete observation, without destroying, or at all affecting, the usual phenomena of life:-- In “following life through creatures we dissect, We loose it, in the moment we detect.” Indeed, we are not able to do even so much as this; for life has already vanished, long before we have come upon the verge of its secret precincts. It is like a Magician, that operates at a distance on every side, but still keeps himself apart, within a narrow circle. If we remain _without_ the circle, we may gaze with never-ceasing admiration, on the wonders that play in rapid succession before our eyes. But, if we rush within, to force an avowal, of the secret energy that produces them, the enchanter and the enchantments alike are fled. The brain, then, and the various nerves of sense in continuity with it, may, when taken together, be considered as forming one great organ, which I would term briefly the _sensorial_ organ, essential to life, and to the immediate production of those mental phenomena which constitute our sensations, and, perhaps, too, modifying in some measure, directly or indirectly, all the other phenomena of the mind. “Dum mens alma caput cerebrique palatia celsa Occupat, et famulos sublimis dirigit artus, Et facili imperio nervorum flectit habenas, Illius ad nutum sensus extranea rerum Explorant signa, et studio exemplaria fido Ad dominam adducunt; vel qui statione locantur Vicina, capitisque tuentur limina, ocelli, Naresque, auriculæque, et vis arguta palati; Vel qui per totam currit sparso agmine molem Tactus, ad extremas speculator corporis aras. His sensim auxiliis instructa fidelibus, olim Mens humilis nulloque jacens ingloria cultu Carceris in tenebris mox sese attolit in auras Dives opum variarum, et sidera scandit Olympi.”