On the other hand, who perceives the natural truths elicited by even his own experiments! That truly great philosopher, Priestly, remained ignorant that his own experiments on blood and air brought to light the principle on which the blood is arterialized, without coming in contact with the air in the lungs; of which experiments the faculty are reprehensibly ignorant at present; also the principle of congelation without cold. It is a general error that men must be philosophers because they are mathematicians and first-rate experimenters, yet do not know what keeps the blood in motion, nor how water becomes ice.
What experiment was ever so absurdly illustrated as that of ice formed in the midst of fire; which is explained by, "evaporation generating cold in a red-hot crucible," and while maintaining that cold is only the absence of heat. The rationale is: the oxygen of water is the hindrance to congelation, which the evaporation carries off, and the remaining elements of the water are compressed into ice. What are the elementary constituents of water, has yet to be learned. Misled by false-directing philosophy, the analysis of a rotten potato, in quest of the cause of the vegetable epidemic, is as wise as were the same scientific procedure taken on the contents of a pustule to discover the cause of the small pox: the result in both cases must be a complete new formation; and in the former, the result could be no preventive information whatever to the planter. To convince planters and remove all timidity, every garden owner should plant an experimental patch with potato peelings, each having an eye; the crop is certain and good, and supplies the cottager with the next year's seed at no expense. The cutting for seed may be of exhausted vegetating power, while the peeling of even the same potato may be as sound as ever. The badly grown potatoes of the previous crop caused those of the following to be of imperfect growth and perishable: hence the general potato-rot.
PHYSIOLOGY AND FUNCTION OF THE SENSES.
By the popular expression, "Evidence of the Senses," is universally understood, the perception, or seeing external bodies by the organs of sense: yet externals are invisible and the senses insentient. This mistake, common among the fathers of every age, has corrupted the prevalent false philosophy tenfold.
The eye is not possessed of sight; neither is colour a property of matter, or it must be indestructible by fire and every other means. The senses should be considered as but mechanical agents for exciting the brain; by which means it is we have our knowledge, the particulars of the whole of which are mental, confined to the brain, and consist, solely, in the cerebral excited scenery of the sensorium. We have no other kind or means of acquiring knowledge, that is, mental information. By the mere organs of sense we know nothing. The knowledge we have by means of the senses exciting the brain, consists in sensations or sensible effects, and, we know nothing but our knowledge, whatever may be thought of externals being objects and immediate objects of our knowledge.
In describing what we know, it is imagined the description is of external bodies, their appearance, qualities, and properties; which, however harmless the mistake throughout busy-life affairs,—as all abide, judge, and are directed by the same kind of evidence,—not so is it in philosophy, which is a description of nature's own mode of procedure; and although it is impossible to describe invisible things, as they are really, they should not be philosophised and reasoned on, as they are not; they are not according to what we know, and can have no resemblance in any manner to sensations, which are all we know by means of them. Instead of knowing by the senses what bodies are, we know only what they are not; modern philosophy is regardless, totally heedless of this most instructive most pointedly directing information, instead of making the just allowance for mental appearances, it materializes every sensation, and imputes the whole to the bodies outside of our own, of which all we can possibly know is but inferential knowledge: it considers our sensations as being qualities of bodies or properties of matter, and maintains that some are physical causes by which certain physical effects are produced. Such may be considered some of the principal reasons why clairvoyance is unintelligible to all the most learned; and so must it ever remain, or until a truer philosophy arises and rescues the great subject from the darkness and errors of a perverting philosophy, the whole of which has to be abandoned before the mind is fitted for the reception of natural truths. We must cease to identify sensations with their unseen, unknown, and but promoting, material causes. In proof of the foregoing, a short review of the senses, their physiology, function, result of the function and use of the result, must prove satisfactory and convincing.
The physiology of a sense, consists in an external organ,—as the eye or ear, its nerves of sensation which spread through the brain, and, the nervous fluid. To each of the senses there belongs a distinct cerebral organ, which, if deducted, leaves nothing to constitute the physiology, but the external organ, the nerves, and nervous fluid; such may be considered the physiology of all the senses, so far as the exciting mental perception is concerned.
The function of a sense is, to act on and excite the cerebral organ, when the nervous fluid is put into an acting state through external circumstances.
The result of the function, is a sensation, of which we have immediate cognizance, by reason of a sensation being a recent change in consciousness. The nervous fluid, not the tubular nervous striæ, is that by which the brain is excited.