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P H Y S I 
exiftent and fucceflive actions. Health is the refult of 
that juft conformation of the organs which enables them 
to perform their functions with eafe. 
The exaCt conformity which fubfifts between the ffruc- 
ture of each organ and the functions it is deftined to 
perform, demonftrates to tiie philofophical eye an intelli¬ 
gent and wife principle, that in the formation of organized 
bodies directs and prefcribes every thing in the manner 
inoft favourable to the end which it propofes. Now 
Stahl could never perfuade himfelf that a being could 
proportion and adapt its organs to the operations they 
are to perform, without pofleffing a knowledge of thefe 
operations, and having already exercifed a judgment with 
refpeCt to them. It is from this that he confounds the 
principle of life with the thinking foul, which, being 
inceftantly prefent in every part of the body, direCts and 
difpofes them according to its own views, and to the end 
that it propofes in the continual development of the 
aCtions it is to conduCt. 
The formation, the ftruCture, duration, and movements, 
of the body, do not belong peculiarly to it, as it is only a 
paflive fubjeCt on which the foul imprefles and realifes 
the idea of the phenomena that the has conceived. 
Every thing is derived from the union of the body with 
tiie aCtive forefeeing principle, which governs, according 
to fpecial laws, thofe phenomena which are more parti¬ 
cularly vital, and which are mod independent of the will. 
The immediate aCtion of this latter faculty does not 
require the aftiftance of any other fubftance. The inter¬ 
vention of an intermediate principle would be there fu- 
perfluous ; and Stahl rejects that of the animal fpirits, 
which had been introduced to explain the mechanifm of 
vitality, and which, by overcharging the fcience, etnbar- 
rafles it with a ufelefs hypothefis. 
Two faculties arefufficient for the foul to aCt upon the 
body, and to preferve it in a living ftate ; viz. thofe of 
fenfe and of motion. By the former, the animal learns 
to know the properties of the objeCts by which he is fur- 
rounded, or in which he is interefted, and to eftimate the 
relations that fubfift between thefe objects and himfelf; 
the latter produces the motion of the whole machine, and 
determines all the changes of lituation which it has to 
undergo in its whole, and in its parts. 
The faculty of fenfation has two] modifications, rela¬ 
tive to the two kinds of knowledge which the foul may 
receive by means of that function. The firft of thefe re- 
fides in the organs of fenfe, and is adapted to external 
objects; the fecond eftablifhes its feat in the interior or¬ 
gans, and refers to objeCts that are within, or ideas. 
Sometimes the moving power belonging to the mufcular 
fyftemis difplayed by the fenfible movements ; fometimes, 
concentrated within thefe organs, it excites inteftine mo¬ 
tions, which maintain among their conftituent partsthofe 
relations and that equilibrium which are neceflary to pre¬ 
ferve the tone of each organ. The mufcular apparatus is 
fubfervient to the exercife of the fenfes; and the differ¬ 
ent motions which it imprefles on the body, for thepur- 
pofe of tranfporting it towards or from certain objeCts, 
are always determined by the convenience or inconve¬ 
nience which the body, by means of the fenfes, experi¬ 
ences from thofe objects. The tonic motion, determined 
by the confufed ideas of the principle of life, is difplayed 
in the moft hidden organic parts, in the molt perfeCt re- 
pofe of the voluntary movements. 
The foul gives to its organs the difpofition that is fa¬ 
vourable to the fenfations it wiflies to receive, by virtue 
of the judgment that it exerts refpeCting thefe fenfations, 
before it has experienced them. This judgment is ex¬ 
erted on the relations between the objects that excite 
thefe impreflions, and the aCtual ftate of the body ; and it 
is the intuitive knowdedge of thefe relations that deter¬ 
mines, in all their infinitely-diverfified ihades, the plea- 
fure or the pain which the animal experiences from the 
objeCts that furround it. 
O L O G Y. 
Stahl regards the excretions as the means employed by 
nature to counteract the natural tendency of the body 
towards putrefaction. He believes that the animal hu¬ 
mours are exceedingly difpofed to thicken, and that the 
circulation of the blood is the means made ufe of by nature 
to keep up their original fluidity. One of the caufes that 
moft favour the tendency of the humours to putrefaction, 
is plethora , to which nature oppofes, fometimes the mo¬ 
tion of the folids that diftribnte the blood, fometimes the 
hemorrhagic fluxes which unload the vafcular fyftem. 
Haller was tire firft who endeavoured to aflign to indi¬ 
vidual parts their diftinCt faculties: and he did this with 
fuccefs as far as regards the mufcular fyftem. He ftated, 
that the power of contracting was confined to this fyftem ; 
and that it was perfectly diftinCt from the pow'er of feel¬ 
ing, (or fenlibility as it is now called.) Plain and felf- 
evident as this propofition is, no one feems to have laid it 
clearly down before Haller, and many w’ho have fucceeded 
him feem not to comprehend it. The reafon of this is 
partly, that the name by which Haller tiled to defignate 
this faculty, viz. irritability, was one which many au¬ 
thors ufe to exprefs a great activity of the functions of 
the body in general, or of the mind. Haller divides irri¬ 
tability into two kinds; the one primary and direCt, the 
other fecondary and fympathetic; or, as we fliould fay, 
one voluntary, and the other involuntary. He likewife 
attempted to diftinguifli between irritability in the dead 
and in the living fibre. In this he failed. 
He Whytt oppofed Haller’s opinion that irritability was 
confined to mufcles, on thefe grounds : firft, that he ob- 
ferved contractions in the dartos, which, he fays, has no 
mufcular fibres, and even in the fkin ; fecondly, that red- 
nefs and inflammation occur in every part of the body to 
which irritants are applied. This author’s firft objection 
is met by the faCt, that the corrugation of the fkin is a 
fecondary and Amply mechanical effeCt. His fecond has 
nothing to do with the matter; for rednefs and inflamma¬ 
tion are not contractions. The immediate caufe of this 
irritability has given rife to many conjectures: one of 
thofe which has been generally received is, that irritabi¬ 
lity is intimately connected with fenlibility; or, that it is 
an immediate effeCt of the nervous power. This was 
the opinion of Whytt and Cullen, the former of 
whom endeavours to prove it by the following argu¬ 
ments. 
1. We almoft always obferve the irritability of the 
mufcular organs of the human body to bear a propor¬ 
tion to their fenlibility. Thus, children, and people of 
delicate nerves and very quick feelings, are moft fub¬ 
jeCt to convulfive and fpafmodic difeafes; while, on 
the other hand, old people, and thofe of lefs delicate fen- 
flbility, have a mufcular fyftem that is not fo irri¬ 
table. 
2. Whatever increafes the fenlibility of the mufcles, 
alfo increafes their irritability. 
3. Whatever leflens or deftroys the fenlibility of the 
mufcles, alfo leflens or deftroys their irritability or power 
of motion. 
4. That the motions of irritated mufcles are owing to 
the fenfation excited byfthe ftimulus applied to them, Dr. 
Whytt thinks highly probable, if it be confidered that 
we are in faCt confcious of many involuntary motions 
in our own bodies, proceeding from particular fenfa¬ 
tions either in the organs moved or in the neighbouring 
parts. 
Dr. Cullen was fo fully convinced of the neceftity of 
nervous influence to produce mufcular contraction, that 
he confidered the mufcular fibre to be only a continuation 
of the nervous fibre. 
Haller, as we have faid, ftrenuoully maintained, that 
irritability was quite independent of the nerves, and was 
an inherent power or vis infita of the mufcular fibre. 
Indeed there are feveral circumftances which would 
induce us to believe that irritability is independent of 
nervous 
