146 Proceedings of the Royal Society 
five hours as in muscle-work — say by a street-paviour — in ten hours. 
Although all the changes going on in living tissues may be finally 
resolved into chemical changes, — a fact well illustrated by Dr W. B. 
Richardson, and by Professor Crum Brown’s and Dr Thomas R. 
Fraser’s valuable researches into the connection between physio- 
logical action and chemical composition, lately communicated to 
the Society, — they are distinct from those induced in inorganic 
matter by chemical affinity, and hence the need of connoting the 
energy by the term vital. Now the distinguishing character of that 
energy, whether manifested in plants or in animals, is adaptation 
of all motion to ends. Evolved in the brain, this vital energy is 
manifested as mind, and life is thus spiritualised. I would even 
venture to say that matter is thus immaterialised, for since all 
states of consciousness correlate motion of something, it is not the 
connection of mind with mere ponderable or brute matter we have 
to discuss, but of mind with adapted motions in infinite variety. 
All external impressions received through the senses and exciting 
states of consciousness can be resolved into motions that can be 
exactly measured, in regard to impressions on the eye and ear, and 
all internal impressions passing from one part of the brain or of 
the body to another part, can be resolved also into an energy cor- 
relative with motion, termed vis nervosa. So that psychology by 
this method is, in one sense, a department of physics; in a wider 
sense it is a science or philosophy of nature, and therefore differs 
essentially from modern physiology, which is only a restricted de- 
partment of physiology in the true and ancient sense of the word. 
In fact, the method I adopt is an adaptation of the ancient Aristo- 
telian method to modern philosophy, and in adopting it with me, 
the Faculty of Arts of the University would only return to a for- 
mer arrangement of work. Sir William Hamilton observes on this 
point to the effect, that “ Aristotle’s treatise On the Soul being 
(along with his lesser treatises on Memory and Reminiscence , on 
Sense and its Objects , &c.) included in the Parva Naturalia , and 
he having declared that the consideration of the soul was part of 
the philosophy of nature, the science of mind was always treated 
along with physics.”* 
* Lectures on Metaphysics, vol. i. p. 127. 
