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order, and important questions of logical definition, which we have not suffi- 

 cient time to discuss in their entirety. One thing is obvious on the most 

 cursory perusal of many modern works ; that our physical philosophers — men 

 who are great in their omi sphere of thought — are in the habit of trespassing 

 on domains of metaphysics, mental philosophy, and logic, which they have 

 never studied ; and thus they invest their utterances on these subjects with 

 the halo of their well-earned reputation as Physicists. But a high reputation 

 in one line of thought is no guarantee for ordinary correctness in another. 

 Mr. Darwin's high reputation as a naturalist has certainly not prevented him 

 from exhibiting himself weaker than other men when he has attempted to 

 deal with questions which properly belong to Moral Science. But with 

 respect to the paper and the discussion on it : it is evident that we greatly 

 need a definition of some kind, which will enable us to attach a consistent 

 meaning to the term " Force ; " and that our want of it involves us in hope- 

 less confusion. At present we designate two things, while differing in their 

 conception, by the same term — "physical force " and " mental force." As 

 long as we do this, how is it possible to avoid confusion of thought ? The 

 one is an idea derived from certain phenomena in external nature ; the 

 other from our consciousness of our own voluntary agency. When two 

 trains run into one another, we have an example of physical force. When 

 a great orator persuades a Parliament to do the very contrary to that 

 which they intended to effect, we have an example of mental power. But 

 the two acts diflfer from each other by the entire interval which separates 

 matter from mind. Yet it is not imcommon to hear " mental forces " 

 and " material forces " spoken of as if they were the same thing — nay, it is 

 even asserted that they can correlate into each other. This confusion of 

 thought has enveloped much of the reasoning on this subject in a complete 

 fog ; so that we are in danger of missing our road in places with which Ave 

 are entirely familiar. The use of this and of several other kindred terms is 

 at present in a state of hopeless confusion. It is really high time that 

 some system of definition should be adopted which will enable us to 

 know what we are talking about. At present even eminent physical 

 philosophers use the term force in different senses, and when they apply the 

 same term to denote certain powers of the mind, our confusion becomes 

 inextricable, acrimonious discussions ensue, and after all it turns out that 

 instead of striking at each other, we have been striking at things wholly 

 different, and that the whole has resulted in nothing but a wasteful expen- 

 diture of valuable powfer. How is it possible that any reasoning can end in a 

 useful result, when one man is talking about one thing, and another about 

 a thing quite dilTerent. This loose use of language involves us in endless 

 contradictions. Take for an example the use which is made of the word 

 motion. What does it mean ? Surely, if it has any meaning at all, it can only 

 mean change of position in space. It is that obvious thing which we see every 

 day before our eyes. But we hear people talk of latent motion, or stored-up 

 motion, as though, when the motion of a body ceased, there was not an end of 



