372 
DR. PHILIP ON THE POWERS OF LIFE. 
simple, and was, by their intimate connexion with the more complicated powers, led 
to them ; I shall in the recapitulation, that they may be viewed in both directions, 
begin with the more complicated, which by the same means will lead us to the more 
simple powers. 
BESIDE the mechanical powers, of which the living animal evidently partakes in 
common with inanimate nature, it possesses, we have seen, four distinct powers, ap- 
parently peculiar to itself, having no direct dependence on each other, but each de- 
pending on the other three, for the maintenance of its organs ; the sensorial, the 
nervous and the muscular powers, and the powers of the living blood. 
By these powers are maintained the two systems into which the various functions 
arrange themselves, the vital and sensitive systems, the object of the one being the 
maintenance of our bodies, of the other, our intercourse with the external world. 
THE organs of the sensorial power in man have their seat in the brain. They can 
be excited by no other means than the influence conveyed by the nerves of sensation, 
in the most extended sense of the expression, in every instance called into operation 
by impressions made on their extremities by agents which belong to inanimate 
nature, either existing within our own bodies, or making their impression from 
without ; and, on the other hand, there are no means by which the sensorial organs 
can influence those agents but through the intervention of the powers of the nervous 
system properly so called. The nature of the sensorial power, we have seen, admits 
of no direct intercourse between its organs and the agents of inanimate nature, 
because it operates by properties, which have nothing in common with those of such 
agents ; and as it can only receive impressions from the external world through the 
nerves of sensation, with which it is associated, it can only impress the agents of that 
world through the muscles of voluntary motion, excited by the nerves associated with 
them. Thus it is necessary, as we have by direct experiment found to be the case, 
that the organs of the nervous system should be placed under the control of the 
sensorial power. Through the same channel, we have seen, this power also, in some 
of their functions, controls the muscles of involuntary motion ; and we have reason 
to believe, although the point has not been ascertained by direct experiment, all the 
powers of the living blood. And such, as appears from facts above referred to, is 
its influence on the nervous, and through it, on the muscular power, and we have 
reason to believe on the powers of the living blood, that it can not only excite, but 
impair and instantly destroy all these powers, according to the nature and power of 
the causes which influence its organs. 
The circumstance of the muscular, as appears from facts above referred to, being 
the moving power of the blood in the vessels as well as the heart, greatly extends 
the influence of those powers which control it, namely the nervous power properly 
so called, and the sensorial power acting through it. 
The only respects in which the sensorial power is related to the subject of this 
