48 Wisconsin Academy of Sciences, Arts^ and Letters. 



Brown and the illness of Smith. These are plainly incoherent ; 

 or, in popular parlance, they have nothing to do ^vith each other ; 

 that is, they have nothing in common ; that is, again, no element 

 of one is also an element of the other. 



Suppose, however, I say "I have a book you will like." My 

 total thought again consists of two units, first my possession of 

 the book, second vour likino- the book. But this time one ele- 

 ment is indispensable to each thought, namely ^'the book." That 

 is, the two thought-units have a common factor. This commu- 

 nity is plainly the condition of their coherence. It seems in- 

 deed entirely safe to generalize as follows: If two units have 

 a common factor, an element, that is, which is indispensable to 

 or inseparable from each, they cohere. 



As the common factor is the key to relative usage, it is well 

 to distinguish sharply between strictly common and merely 

 equivalent factors. In doing so it is convenient, how^ever, to ac- 

 cept a usage which indiscriminately ranks them both as common 

 factors and, using this phrase with admitted inaccuracy, to re- 

 differentiate them as common factor varieties. Of these I take 

 up first 



IX. THE SUCCESSIVE OR TWICE THOUGHT COMMON FACTOR. 



The common factor of this type occurs when coherent thought 

 is, in its expression, interrupted. Thus "I have a book will please 

 you," expresses a coherent thought continuously expressed. 

 The expression of this thought may however be interrupted, 

 as in "I have a book. The book will please you." In this ex- 

 pression, so soon as I have finished saying "I have a book", all 

 ideas mentioned withdraw from your immediate attention. ]^one 

 of them will reappear without a special invitation — that is, if 

 you be a faithful listener. Wishing you now to think of one 

 of them as factor also of a second thought, I must recall it to 

 your attention. Accordingly I continue with ^The book will 

 please you". The idea named by ^^book" appears, then, twice 

 in your mind, once as a factor of each thought presented. That 

 is, it is a twice-thought factor. It is merely speaking from a 

 different point of view^ to say that) this idea appears later on the 



