I 
PHYSIOLOGY. 
conclusion, that there is none which has 
not formerly, constituted part of a body like 
itself, from which it has been detached ; all 
have participated of the life of another 
body, before the vital motions were carried 
on independently in themselves ; and it is, 
indeed, through the means of the vital pow- 
ers, inherent in the bodies of which they 
formed part, that they have been so far de- 
veloped as to become susceptible of an 
isolated life. For although copulation is 
necessary in the act of reproduction in se- 
veral species, it is by no means an essential 
circumstance, and does not, therefore, 
change the nature of generation. In re- 
ality, then, the peculiar powers of living 
bodies have their origin in those of the pa- 
rents ; this is the source of the vital im- 
pulse, and, consequently, it follows, that 
life is only produced from life, and that no 
other exists, except what has been trans- 
mitted from living bodies to living bodies, 
in an uninterrupted succession. 
Since we cannot go back to the first ori- 
gin of living bodies, our only resource in 
investigating the true nature of the powers 
which animate them consists in examining 
their structure, and tracing the union of 
tlieir elements. Our knowledge of these 
points is too imperfect for us to draw all the 
necessary Inferences. The minute branches 
of vessels and nerves, and the intimate 
structure of the organs in general, elude 
our imperfect means of research : our ana- 
lysis of fluids is also very incomplete, and 
there are, probably, several which we have 
no means at all of subjecting to examina- 
tion. Yet, though our knowledge of or- 
ganization be not sufficient to enable us to 
explain all the facts presented to our obser- 
vation by living bodies, we may, by means 
of it, recognise them, even in an inactive 
state, and trace their remains after death.> 
No inanimate matter has that fibrous and 
cellular texture, nor that multiplicity of 
volatile elements which form the characters 
of living bodies, whether alive or dead. 
Thus, while inorganic solids are only com- 
posed of many-sided particles, attracting 
eacli other by their surfaces, and receding 
only for the purpose of separating ; white 
they are resolved into a very limited num- 
ber of elementary substances, and are 
formed merely by the combination of these 
elements, and the aggregation of these par- 
ticles ; while they grow only by the ‘juxta- 
position of new particles, which are cffepo- 
sited exteriorly to those already existing, 
and are destroyed only by the mechanical 
separation of their parts, or the decompose, 
ing agency of chemical means j organized 
bodies, made up of fibres and laminae, 
whose intervals are filled by fluids, are re- 
solved almost entirely into volatile elements, 
grow on bodies similar to themselves, and 
separate from these only when they are suf- 
ficiently developed to act by their own 
powers ; constantly assimilate foreign mat- 
ters to themselves, and, interposing these 
between their own particles, grow by the 
operation of an internal power, and perish 
at last by this interior principle, indeed, by 
the very effect of their life. 
An origin by generation, a growth by 
nutrition, and a termination by death, are 
the general characters common to all orga- 
nised bodies ; and if several of such bodies 
possess these functions only, and such as im- 
mediately depend on them, and have only 
the organs required for their performance, 
there are many others exercising particular 
functions which require appropriate organs, 
and also modify the general functions and 
tlieir organs. 
Of all the less general powers, which pre- 
suppose organization, butw'hich do not seem 
to be necessary results of structure, those 
of sensation and voluntary motion are the 
most remarkable, and exert the greatest in- 
fluence over the other functions. We are 
conscious of the existence of these powders 
in ourselves, and we attribute them, by an 
analogical mode of reasoning, to many other 
beings, which we therefore name animated 
beings, or animals. They seem to be ne- 
cessarily connected together ; for the idea 
of voluntary motion contains in itself that 
of sensation ; since volition cannot be con- 
ceived, without desire, and without a feeling 
of pleasure or pain. The goodness, which 
we observe in all the works of nature, will 
not allow us to believe that she has formed 
beings with the power of sensation, that is, 
with a susceptibility of pleasure and pain, 
without enabling them at the same time to 
approach to the one and fly from the other, 
at least to a certain degree. And, if, among 
the too real misfortunes which afflict our 
species, one of the most affecting is the 
sight of a man of sensibility deprived by su- 
perior force of the power of resisting op- 
pression ; the poetic fictions, most apt to 
excite our pity, are those which represent 
sensible beings inclosed in immoveable bo- 
dies ; and the tears of Clorinda, flowing 
with her blood from the trunk of a cypress, 
ought to arrest the blows of the most 
savage man. 
