362 
DR. PHILIP ON THE POWERS OF LIFE. 
another, and that by its vital properties alone ; for it is evident that the properties 
operating here have nothing in common with those of any of the principles of inani- 
mate nature. In the results consequently, we have seen all analogy with the phe- 
nomena of these principles, for the first time, lost ; and necessarily so, none of the 
properties of the agents of that world being immediately employed in their pro- 
duction. 
The nerves of sensation, it appears from what has been said, convey not the nervous 
influence properly so called. The influence they convey is of a nature essentially 
different from that by which the muscles are excited and the functions of secretion 
and assimilation maintained. They sufficiently partake of the nature of the sensorial 
organs to be capable of directly impressing them, and thus the latter receive all their 
impressions whether originating from without or within our own bodies. 
On the other hand, — that is, that the sensorial organs may, without contact with any 
of the agents of the external world, impress those agents, — a more complicated ma- 
chinery is required. The various nerves of sensation are the only means required for 
conveying impressions to these organs ; but so simple an apparatus is not sufficient to 
convey to, and impress on, the materials of the external world, the dictates of volition. 
The powers of the nervous system are here called into operation by the sensorial powers, 
to which they are subjected ; for it appears from many experiments, detailed in the 
Philosophical Transactions for 1815 and in my Inquiry into the Laws of the Vital 
Functions , that as the muscular is independent of the nervous power, but subjected 
to its influence, the nervous is independent of the sensorial power, but, in like manner, 
subjected to the influence of this power. In the case before us the nervous, influenced 
by the powers of the sensorial organs, supply a certain set of nerves with the stimu- 
lus which excites the muscles of voluntary motion, the immediate agents by which the 
materials of the external world are impressed. 
I have had occasion to refer to the great variety of the phenomena of life, as one 
cause of their apparent obscurity. Such is their variety that we are at first view lost 
in attempting any arrangement or even enumeration of them. An essential step 
towards their arrangement, as appears from what has been said, is their division into 
those which are the immediate results of the cooperation of the principle of life with 
the principles of inanimate nature, and those which have no immediate dependence 
on the latter powers ; for all our functions mediately or immediately depend on the 
operations of the agents of inanimate nature. All are more or less directly excited 
by impressions originating in their agency. 
The most purely sensorial functions, our pleasures and pains, are as dependent, 
though more remotely, on the excitement maintained by them as the functions of the 
organs immediately impressed by them. Have not the excitements of memory as 
much originated in their impressions, as their more direct effects on the part im- 
pressed ? And when the nature of our bodies and the circumstances in which we are 
placed are duly considered, what other result could be expected ? Our organs, being 
