To the constitution of this earth are plants, living forms destitute of feeling, hearing, sight, or indeed any sense known to us, adapted--yet according to their kinds they know what nutriment to refuse or reject; they are subject to the influence of temperature and of light and darkness; some court the broad glare of the sun, others flourish only in the shade. The same observations apply to certain of the lowest forms of animal organization, which lead a vegetable life, and appear not to be aware of their own existence. Nor, indeed, is it until we ascend high in the scale of animal being, and arrive at a point at which the senses are more or less developed, and in accordance with this development, that of mind also, (for we can use no other term,) that we discover a decided consciousness of existence, as manifested by anger, fear, and other passions; by watchfulness, sensibility to pain and pleasure of a mental kind; a recourse to artifice or to force as a means of gaining certain ends; and other proofs of a something--call it mind, or any other name--to which the senses appeal. For, let us remember, it is only in a certain sense that the eye sees, or the ear hears; in the former instance, nothing more than an image of objects is inversely reflected on the retina, and yet the mind recognises these objects in their proper position; and what is more, not double, though the same object is figured on the retina of each eye, or, in the case of insects, on the retina of scores of eyes. In hearing, the minute auditory nerves merely receive an impulse from the vibrations or wavelets of the elastic atmosphere, and this constitutes what we call noise, tones, music, voice. But these tones or noises are in the mind only; they are not appreciated by the exercise of any other sense. Having thus briefly endeavoured to show the harmony of the general order of nature, as far as our globe and its animal and vegetable forms are concerned, we shall proceed to the consideration of another portion of our subject, and commence with it a fresh chapter. CHAPTER II. MAN'S KNOWLEDGE OF THE QUALITIES OF MATTER OBTAINED THROUGH THE MEDIUM OF THE SENSES. If we reflect upon man, beginning with the savage, and ending with the philosopher, we shall find, that although the mental difference, or rather the extent of acquired knowledge possessed by each respectively, is very great, that the little the one possesses, and all that the other may boast of, are based upon certain simple principles, seized upon by the mind through the medium of the senses, and made more or less the subjects of consideration and research.