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we have chiefly to do at present, but with tne positive truth 
that he is unwittingly teaching. His experiment demonstrates 
what is exactly to our purpose — namely, that the true initiatory 
force in the case is that which raises the shutter. This is not 
light, nor is it any other mode of mere motion ; it is an 
energy which “ produces motion.” Without this, which is 
really a 'property of the mind of him who raises the shutter , 
even the finely arranged instrument which Grove uses in his 
very interesting experiment * would be still for ever — that is, 
the matter which is under experiment, while it is capable of 
being put in motion by mind, is itself inert or utterly incapable 
of spontaneous change. Grove himself expresses this in one 
of his own statements. Speaking of an experiment, he says — 
“ A voltaic combination is thus formed, and electricity, heat, 
light, magnetism, and motion produced at the will of the 
experimenter.” This “ will of the experimenter,” or, as we 
should prefer to say, this experimenter himself, is transparently 
the true cause in the case, and in every case in which matter 
is the subject of experiment. True science, therefore, shuts 
us up to the great truth that mind alone is possessed of that 
force which is the true and efficient cause of motion or change 
in all its modes. 
But we must return seriously to the notion that force is 
matter. The truly great names of Boscovich and Faraday are 
committed to this wild hypothesis. Faraday says — “ Gravita- 
tion is a property of matter depending on a certain force, and 
it is this force which constitutes matter.” This statement 
expresses the conclusion at which he arrives by a somewhat 
elaborate argument given in the form of a letter addressed to 
Richard Taylor, Esq., and dated Jan. 25th, 1844. f 
Mr. Faraday's argument is partly metaphysical. He says, 
A mind just entering on the subject may consider it difficult 
to think of the powers of matter independent of a separate 
something to be called the matter, but it is certainly far more 
difficult, and indeed impossible, to think of or imagine that 
matter independent of the powers.” This is merely the argu- 
ment which we have already considered in proving the reality 
of substance, only it comes under notice in a peculiar phase. 
We have here to do with what are called “ powers,” and two 
of these are specified in the course of the argument — the 
conduction and isolation of electricity. Shellac, for example. 
* The ingenious arrangement of materials which form the instrument 
itself is also the work of the mind, intelligence, and will of its constructor, 
t Experimental Researches in Electricity , Vol. II., page 293, edition 1844. 
