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NATURAL SELECTION 
ix 
The Origin of Consciousness 
The question of the origin of sensation and of thought 
can be but briefly discussed in this place, since it is a subject 
wide enough to require a separate volume for its proper 
treatment. No physiologist or philosopher has yet ventured 
to propound an intelligible theory of how sensation may 
possibly be a product of organisation 5 while many have 
declared the passage from matter to mind to be inconceiv- 
able. In his presidental address to the Physical Section of 
the British Association at Norwich, in 1868, Professor Tyndall 
expressed himself as follows : — 
“ The passage from the physics of the brain to the corre- 
sponding facts of consciousness is unthinkable. Granted that 
a definite thought and a definite molecular action in the brain 
occur simultaneously, we do not possess the intellectual organ, 
nor apparently any rudiment of the organ, which would 
enable us to pass by a process of reasoning from the one 
phenomenon to the other. They appear together, but we do 
not know why. Were our minds and senses so expanded, 
strengthened, and illuminated as to enable us to see and feel 
the very molecules of the brain, — were we capable of following 
all their motions, all their groupings, all their electric dis- 
charges, if such there be, and were we intimately acquainted 
with the corresponding states of thought and feeling, — we 
should be as far as ever from the solution of the problem, 
1 How are these physical processes connected with the facts of 
consciousness ? ’ The chasm between the two classes of 
phenomena would still remain intellectually impassable.” 
In his latest work (An Introduction to the Classification of 
Animals ), published in 1869, Professor Huxley unhesitatingly 
except in the same sense that the action of man or of any other intelligent 
being is a first cause. In using such terms I wished to show plainly that I 
contemplated the possibility that the development of the essentially human 
portions of man’s structure and intellect may have been determined by the 
directing influence of some higher intelligent beings, acting through natural 
and universal laws. A belief of this nature may or may not have a founda- 
tion, but it is an intelligible theory, and is not, in its nature, incapable of 
proof ; and it rests on facts and arguments of an exactly similar kind to 
those which would enable a sufficiently powerful intellect to deduce, 
from the existence on the earth of cultivated plants and domestic animals, 
the presence of some intelligent being of a higher nature than themselves. 
