DR. PHILIP ON THE POWERS OF LIFE. 
363 
composed of the same materials as the world which surrounds us, can only be directly 
influenced by agents of their own nature ; and from that world, and by the medium 
of those organs, all the materials, not only of our acquired knowledge*, but of our 
enjoyments and our sufferings, are derived. 
And as on the one hand, all our functions are more or less immediately excited by 
impressions made by the agents of the external world on organs composed of mate- 
rials of their own nature, on the other, we have no power of influencing them, but 
through similar means. The only means of exciting our mental functions are the im- 
pressions of those agents on the organs of sense, and our only means of operating 
beyond our own bodies are through our organs of motion. Even when by our mental 
powers we influence those of other sentient beings, it is as much, though not so di- 
rectly, by impressing the agents of the external world by the latter organs, as when 
we raise a weight or throw a stone. 
SUCH is the general outline of the vital and sensitive systems ; and the manner 
in which the various powers of the living animal are related in the formation of these 
systems. By the foregoing means, the nervous power maintains the vital functions 
properly so called ; and the sensorial power is brought to cooperate with the powers 
of inanimate nature, powers which have no properties in common. 
IT appears from the facts adduced in my paper on the Nature of Death, published 
in the Philosophical Transactions for 1834, that the vital and sensitive systems obey 
very different laws, the difference depending on the vast difference in the nature of 
the sensorial and nervous powers, the leading powers which pervade all their depart- 
ments, and to which all their other powers are subservient. 
These other powers, it appears from what has been said, are the same in both, 
namely, the muscular power and the powers of the living blood, and, in the sensitive 
system, the nervous power itself ; for in this system all the other powers of the living 
animal are directly subjected to the sensorial power, while none of the powers of 
the vital system have any direct influence on it, their influence on the sensorial 
power being through the medium of its organs, the structure and wellbeing of 
which immediately depend on the vital powers. 
In other respects also the laws of the two systems essentially differ. Nor will these 
differences surprise us, when it is recollected, as appears from the facts which have 
been stated, that while the leading power in the vital system is one of those powers 
which operate in the external world ; that of the sensitive system not only possesses 
no properties in common with the agents of inanimate nature, but depends on a set 
of organs unapproachable in their healthy functions by any such agents. 
When the facts adduced in the paper just referred to, and that on the Nature of 
* We are bora with the knowledge which is immediately essential to our existence. The infant knows as 
well how to suck and how to breathe as the adult. See my paper On the Nature of Death . 
3 A 2 
