4 Wisco7isi?i Academy of Sciences, Arts find Letters. 



time and in the same relation a part of the thing known and 

 used. 



Human knowledge and human liberty fundamentally 

 planted in this union of the physical and spiritual, as we 

 here conceive them, show empirically two lines of limita- 

 tion. The first of these appears in connection with the 

 brain, the medium by which the mind receives influences, 

 and the instrument by which it communicates energies. We 

 . may pass at once to the extreme conclusion which science is 

 approstching, that the nervous system in man, with its great 

 centre, the cerebrum, is constructed throughout with definite 

 lines of inner and outer movement. Organic connections 

 differ from mechanical ones in admitting a greater variety 

 of offices, and allowing a freer substitution of one organ or 

 one method for another; yet a distinct constructive purpose 

 rules an organism as it rules a mechanism. The definite- 

 ness of the nerves and of the exterior termini of nerves in 

 the nervous system carries with it a corresponding definite- 

 ness of offices both in them and in the great nerve-centres. 

 Exactness in superficial relations without exactness in inte- 

 rior ones, would be futile, the meaningless juncture of order 

 and disorder. The distribution and precision of the surface in- 

 dicate like exact inner relations in completion of the one plan. 

 Observation of the effects of obstruction and of disease in 

 the brain, and of artificial irritation of its different locali- 

 ties, serves also to disclose explicitness of office combined 

 with organic fiexibility. 



There is nothing in this which liberty may not easily ac- 

 cept. This dependence of the mind on the body gives- strict 

 conditions to liberty, but does not take away its first terms. 

 The tool is an instrument to the hand; the hand is an instru- 

 ment to the bra,in; the tool, the hand, and the brain are con- 

 joint instruments to the mind. The workman cannot go 

 beyond the possibilities of his tools. His circuit of liberty 

 lies within those possibilities. The mind united to the body 

 receives from it what we may call two sets of limitations, or 

 two sets of powers as we choose to regard them: those which 

 pertain, in the senses, to the ingress of knowledge, and those 

 which pertain, in the muscular system, to its egress in ac- 



