_The Unknown_.--The arguments you have used are those which are generally employed by physiologists. They have weight in appearance, but not in reality. They prove that a certain perfection of the machinery of the body is essential to the exercise of the powers of the mind, but they do not prove that the machine is the mind. Without the eye there can be no sensations of vision, and without the brain there could be no recollected visible ideas; but neither the optic nerve nor the brain can be considered as the percipient principle--they are but the instruments of a power which has nothing in common with them. What may be said of the nervous system may be applied to a different part of the frame; stop the motion of the heart, and sensibility and life cease, yet the living principle is not in the heart, nor in the arterial blood which it sends to every part of the system. A savage who saw the operation of a number of power-looms weaving stockings cease at once on the stopping of the motion of a wheel, might well imagine that the motive force was in the wheel; he could not divine that it more immediately depended upon the steam, and ultimately upon a fire below a concealed boiler. The philosopher sees the fire which is the cause of the motion of this complicated machinery, so unintelligible to the savage; but both are equally ignorant of the divine fire which is the cause of the mechanism of organised structures. Profoundly ignorant on this subject, all that we can do is to give a history of our own minds. The external world or matter is to us in fact nothing but a heap or cluster of sensations; and, in looking back to the memory of our own being, we find one principle, which may be called the _monad_, or _self_, constantly present, intimately associated with a particular class of sensations, which we call our own body or organs. These organs are connected with other sensations, and move, as it were, with them in circles of existence, quitting for a time some trains of sensation to return to others; but the monad is always present. We can fix no beginning to its operations; we can place no limit to them. We sometimes, in sleep, lose the beginning and end of a dream, and recollect the middle of it, and one dream has no connection with another; and yet we are conscious of an infinite variety of dreams, and there is a strong analogy for believing in an infinity of past existences, which must have had connection; and human life may be regarded as a type of infinite and immortal life, and its succession of sleep and dreams as a type of the changes of death and birth to which from its nature it is liable. That the ideas belonging to the mind were originally gained from those classes of sensations called organs it is impossible to deny, as it is impossible to deny that mathematical truths depend upon the signs which express them; but these signs are not themselves the truths, nor are the organs the mind. The whole history of