$2 Human Physiology. 



ethereal class of philosophers deny both matter and force, and 

 admit only of sensation and one of the most distinguished 

 has denned a lamp-post, against which one may break his 

 head in the street "a permanent possibility of a sensation." 

 Mr. J. S. Mill says, "We never touch matter even if it 

 -exist, and that we never see it is admitted alike by physiologist 

 and metaphysician, for vision is merely a mental affection, 

 called up by an impulse on the optic nerve, made by the move- 

 ment of the luminous ether, which not the chair or table, but 

 the force existing and acting external to the chair or table, or 

 other object, radiates off." Huxley says, " Every form is force 

 visible; a form of rest is a balance of forces; a form under- 

 going change is the predominance of one over others." We 

 will, therefore, consider force and see if we know any more 

 about it than we do of matter, of which the greatest discoveries 

 of science only reveal more and more the unfathomable mys- 

 teries. " We push back the mystery of nature one step," says 

 Professor Tyndall, "but it is as impenetrable as ever." Pro- 

 fessor Huxley admits that "no ultimate fact in nature is 

 known;" and the ultimate facts seem to belong to the infinite 

 and incomprehensible, like infinite space and infinite duration, 

 -which no intellect can grasp no mind conceive. 



