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mixture of blue and yellow is neither blue nor yellow, but green, &c.; so that there is no particular state in which matter can be said to be in its natural state; for every state may be called its natural one, as it continually undergoes a change of form. The same substance is found in a solid state, in a fluid state, and in an æriform state. This change is universal throughout Nature. Bodies are composed of a number of elements, and these elements are continually undergoing a change ainong themselves. There are innumerable gradations in the nature or kind of bodies : some are entirely different from each other; others are very similar to one another; while others again have only some properties in common. Some substances are very active, minute, and penetrating; while others are gross, and alinost inactive. It is in the nature of every substance to preserve its identity; and, when it fails to do that, it is overpowered by some other substance. This is in unison with the law of causation, that no weaker cause can overcome a stronger one.
From these remarks, it would appear, that phenomena are determined by the nature and condition of their causes ; and that causes are determined by the nature of the elements which compose them; thus, a cause will always be the same, and will produce the same effect, under the same circumstances, provided its elements be the same. The constitution of bodies depends upon the mutual affinity which subsists between their elementary particles; for instance, the elements of wood are different from the elements of iron,--the elements of iron are different from the elements of glass, &c.; but all these substances may have some elements in common; for instance, some of the elements of the spirits of wine may be the same as some of those which constitute water,-heat may have some elements in common with electricity,-and electricity may have some elements in common with the vital principle. But, that none of these substances are identical, is obvious, because the phenomena which they produce are different. It is true that electricity will produce some phenomena in common with life; but, as their phenomena are not precisely the same, in all respects, it would be contrary to reason and experience to infer, that the causes of these phenomena are identical.
From all the above considerations, we have reason to conclude, that, what we call life, or vital principle, is a real substance, pervading the bodies of animals and vegetables ; that this substance is very minute, active, and penetrating, similar in our ideas to heat, electricity, or any other minute substances; but that it is as different from any of these, as one of these is from the rest. This difference, according to the rule which we have laid down, depends upon the nature of its
elements, and is governed by the law of elementary affinity. We do not know what matter is; but, if we find that the phenomena of two bodies of matter are the same, we infer that the bodies which produce them are also the same. Philosophy consists in the comparison of causes and effects,-not in hypothetical quibbling about first causes.
The sum total of the above argument is this :--that Life is a fine, active substance, having a real, material existence, and subject to the laws of matter, but that it differs in its composition from any other modification of matter; it has some properties in common with electricity ;-it has some properties in common with caloric; and it has some properties in common with other modifications of matter: but, as all its properties are not the same as those of any other body of matter, its phenomena must be different from those of any other; for instance, water has properties in common with spirits of wine; lead with wood, glass with stone, &c.; but, as some of their properties are different, their phenomena also must be different. These bodies, and their phenomena, have a relation with our senses; we, therefore, can demonstratively prove their difference; but, as caloric, electricity, light, and life, are too minute to bear a relation with our senses, we prove their difference by inference from their phenomena.
I have now, I hope, said enough to prove the existence and situation of the vital principle; and to draw a comparison (which is all that philosophy can do,) between it and other modifications of matter. It was my intention to say a few words respecting the origin, the preservation, the mode of action, and the decay of this principle; but I fear that I have trespassed too long already, by discussing a subject which may appear uninteresting, but which is of the greatest interest in itself, and to society. Mankind have laboured with great industry to find out the nature and composition of inanimate matter, in order to apply that matter to the cure of disease; but, it seems as if they had forgotten that disease affects living, and not dead, bodies. Where is the use of the knowledge of a drug, unless we have a knowledge of the body on which the drug is to act? Disease has no relation with a dead body; its relation is with the living. If the relation of disease is with the living body, the relation of the remedy must be also with the living body: where is the use, therefore, of examining the nature of the remedy without examining the nature of the body on which that remedy is to act? Butto return :
The vital principle indicates design, in both animals and vegetables; this design is manifested by the process of growth, reproduction of parts, and many other vital pheno
In the inferior orders of animals, a whole limb, or even the whole head, will be reproduced. This I have frequently witnessed. After decapitating a great number of snails, their heads were reproduced before the end of three months from the time it was done. By dividing earth-worms, also, I found that every piece produced a perfect worm, in a few weeks. The polypus may be divided into dozens of pieces, and every piece will become a perfect animal. Do not the results of these experiments clearly prove, that life is a general thing, capable of being divided and multiplied, reduced and increased, precisely in the same manner as any other species of matter? If life were an unity in every individual body, how could one body be multiplied into two bodies, and each of these become as perfect as the original? This phenomena of reproduction is very manifest in vegetables also, for a tree may be multiplied into a great number of trees, by slips being inserted into the ground. Can we shut our eyes against those striking phenomena, and cry out that life is something which we do not understand, and that it is not governed by the laws of matter? It is true, as has been already said, that we do not understand what the essence of life is; but, I would ask, do we know what the essence of any kind of matter is? Our knowledge consists in comparing different modifications of matter.
This phenomenon of design is evident during the whole life of bodies. When a body is perfect, nothing but growth and nutrition, with other necessary phenomena attending them, go forward ; but, as soon as a member, or any other part of the body, is removed, another member, or part, of the sanie kind as the original, is produced in its stead; nay, in some cases, as when polypi, leeches, earth-worms, &c. are divided, Nature, through the agency of the vital principle, finds it easier, or more conducive to her purposes, to multiply an animal, or vegetable, into numerous bodies of a similar kind, than merely to endow the original body with its former perfection.
This power of reproduction is not nearly so strong in the higher order of animals as in the lower. In the former, a whole limb, or a whole bone, &c. will not be reproduced, but a part of a bone, muscle, &c. A number of proofs of this kind might be brought forward to show that a principle exists in the bodies of animals, and vegetables, which is the cause of their organic movements; and that this principle preserves the entity, and identity, of such bodies ;-it feels their want, and supplies them ;--it regulates their organic motions ;-it gradually becomes diminished, and they decay. In infancy, it is small in quantity, but concentrated and vigorous : it, at this
time, has a strong affinity for tangible matter, which it assimilates into bodily structure: during manhood, its affinity for the tangible parts is not so powerful, and its quantity becomes diminished, and, perhaps, its quality changed towards the advancement of years.
A question will here naturally arise,--If the vital principle preserves the body, what is that preserves the vital principle.? This question involves much consideration : it must be answered by comparison. The existence and phenomena of tangible matter are proved by their relation with the senses. T'he existence of the vital principle is proved by induction, from a consideration of its phenomena. The phenomena are proved by their relation with the senses. We know that matter exists, but we do not know how it came to exist. We know also that life exists, but we do not know how it came to exist. As we do not know the cause of either, further than that they indicate Power, Wisdom, Intelligence, Foreknowledge, &c., we conclude that both, and every thing, were produced by the same cause. Admitting, therefore, that life came into existence by the same power as other modifications of matter, we proceed to show how its identity may be preserved,-- how it may be propagated and multiplied,
-how it may form the different modifications of structure.
We find that some parts of the body are formed of skin, some of flesh, some of brain and nerves, some of bloodvessels, some of gristle, some of different kinds of membranes, some of bone: there is liver in one part, heart in another, lungs in another, &c. This may be accounted for by admitting that the vital principle is differently modified in these parts. As the vital principle is the cause of the structure, the structure must be modified according to the modification of the vital principle; for instance, one portion of the vital principle is modified to form bone, another to form brain, another to form liver, &c. In vegetables, one portion is modified to form bark, another to form the woody fibres, another to form pith, &c. The life of one animal must be modified differently from that of another; and the life of vegetables from that of animals, &c. If this were not the case, and if the vital principle did not possess the power of preserving its own identity, and, consequently, preserving the identity of the body, men might become snails, horses might become flies, and sheep might become mulberry-trees : but the life of the body is modified, so as to preserve the identity, &c. of that body. This modification depends upon its elementary constitution; and the nature, or elementary constitution, of every individual life, was, probably, determined at the time of creation.
It follows, from the above remarks, that no change can take place in the structure, without a change first in the vital principle; but, if the vital principle becomes changed in its condition, the structure also will become changed. The vital principle may become, in a degree, changed in its condition by several external causes; the chief of which are air, food, and climate. This change constitutes predisposition, either to disease or to health, or, lastly, to any modification of the structure. As the life of one seat may have a nearer relation with any of these causes than that of another, especially if the cause is powerful, the bodily form may become in a degree altered. A successive application of the same causes, through several generations, may produce an evident alteration in the organization of animals. This phenomena is sufficiently obvious in both animals and plants: they alter their form according to the nature of the air, food, climate, &c. with which, and in which they live. This will be accounted for upon the principle that life is differently modified in every seat; and that each modification, in unison with the law of affinity, has a different relation with the external causes. This relation may tend either to increase, or diminish, the activity of the life of particular seats; or it may merely alter its condition, without altering the degree of its activity.
Nature is a circular chain of causes and effects. Causes join and produce effects ; these effects again become causes for other effects; and this chain of causation is universal and constant. The atmosphere is universal, as it regards terrestrial beings; and it is a common support to them all. The life of one being, in a state of nature, does not depend upon another. The elements of the vital principle are common to all; they pervade the universe, and extend their influence over all animated Nature. Fire consumes the tangible parts of bodies, and converts their natural structure into another form ; so does the vital principle consume the atmosphere, and become united with its vital elements : it converts the food to the nourishment of the body, and preserves itself from decay by its affin for the elements of life, diffused throughout the universe. Trenutnost
There are two supporters of life; these are air and food This may be proved both by analysis anynthesis. Cause have a relation with their effects, and cts cannot exi independent of their causes. A mere on is no prorf a causation; for a succession of events e plaer any relation between these events causation, we must prove successi of the cause in the effect, or a dir cause and effect. This must analysis; for instance, I ma already in the room may