166 Wisconsin Academy of Sciences, Arts, and Letters. ^mM 



states or acts, as depicted or represented ia the changes of the 

 bodj. It is also held to be not simply numerically different from 

 the body, but radically different in substance. The body is said 

 to be material, the mind immaterial. It cannot, therefore, possess 

 the properties of matter. If not, then it cannot, by the terms of 

 the case, be made cognizable by the senses, since they appear to 

 be fitted to reach only to material impressions. Mind therefore, 

 as mind, cannot be submitted to physical tests or examination, 

 though the body can be. Its acts and states cannot be directly 

 made known by such means. They can only be made known to 

 other minds by certain signs, or in other words, certain acts and 

 states of the body which is regarded in a certain sense as an in- 

 strument of the mind. Bat these signs would be without any 

 significance whatever, if it was not for certain modes of interpre- 

 tation possessed by animals, and in various degrees of perfection. 

 The only way, so far as is known, that they have for finding out 

 the meaning of these signs, is by their own experience. They 

 find by observation that the mutual acts and states are more or 

 less invariably associated with certain states or acts of the body. 

 So when they observe other animals in the same bodily states, or 

 performing the same acts, they infer the corresponding mutual 

 states that they have found connected therewith, in their own ex- 

 perience. In this indirect way alone can they discover the men- 

 tal condition of other animals. 



One mind cannot, so far as we know, commune directly, unless 

 under rare circumstances, with another, during the continuance of 

 physical life. But ordinarily, each individual mind may kno^ 

 directly, without the intervention of such signs, many, if not most, 

 of its own states and acts. They take place in what is called self-con- 

 sciousness, which is, in my opinion, the chief, if not the only kind of 

 consciousness we have. These mutual states and acts then, though 

 they cannot be directly reached by physical tests, and are not 

 open to sense observations as physical objects are, may neverthe- 

 less be submitted to the tests of immediate self-observation. We 

 can secretly know often what passes in our own minds, and with 

 the utmost clearness, while the observer, who looks upon our 

 bodies from without, cannot many times so much as suspect what 



