tactile sensation will be experienced as if at the end of the stick, where, however, it plainly cannot be. It is the mind alone which feels, but which, by a peculiar faculty of localisation or extradition, seems to remove a feeling exclusively its own, not only to the outside of itself, but to the outside also of the walls of its fleshly tenement. And as it is with pain or touch, so it is with every sensation with which any of the so-called secondary qualities of matter are identical. If I look at, or smell, or taste a blood orange, the sensation of colour, or scent, or flavour I receive is entirely and exclusively my own, the orange remaining quite unconscious of its own redness, or fragrance, or sweetness, and not, indeed, possessing in itself any real qualities of the kind. For to take redness as an example; how does the sensation of it or of any other colour arise? The waves of a certain very attenuated medium, the particles of which are vibrating with vast rapidity but with very different velocities, strike upon an object and are thrown off in all directions. Of the particles which vibrate with any particular velocity, some are gathered by the optical apparatus of the eye, and deflected so as to impinge on the retina and on the fibres of the optic nerve therewith connected, producing in these fibres a change which is followed by other changes in the brain, which, again, by virtue of some inscrutable union between the brain and the mind, create a feeling or consciousness of colour. What the particular colour shall be, depends either on the rate of motion in the vibrating medium or on the character of the retina; and if, while the former remained the same, the other were to be altered, or if two persons, with differently formed retinas, and one of the two colour-blind, were to be looking, what had first seemed red might now seem green, or what seemed red to one spectator might seem green to the other. But as the same object cannot itself be both red and green at the same time, it follows that what are called its redness and greenness are not in it, but in the spectator. Similarly, the sounds which an object appears to give forth neither are nor ever were in it: they originate in the mind of the hearer, and have not, and never have had any existence elsewhere. 'If the whole body were an eye, where,' asks St. Paul, 'were the hearing? If the whole were hearing, where were the smelling?' and Professor Huxley more than meets the drift of the Apostle's questions by pronouncing it 'impossible to imagine but that if the universe contained only blind and deaf beings, darkness and silence would reign everywhere.'