92 ROYCE— PRINCIPLES OF THEORETICAL SCIENCE. [April 19, 



wealth, the definite structure, the determinate range of variation of 

 fundamental concepts, the distinctly limited list of categories with 

 which the logician apparently has to deal, together constitute one of 

 the most striking results of the investigation. The thought forms, 

 the kinds of conceptual structures which are possible, are certainly 

 not yet thoroughly known, and their range may prove to be very 

 far greater than we yet suspect. But the notable fact is that they 

 appear to be built up upon a few fundamental types, which remind 

 one by analogy of some such natural types as the vertebrate skeleton, 

 or as the type of the insects. With endless variations in detail, each 

 of these great types is built up in its own way, and preserves its 

 morphological identity through its variations. The thought-types 

 are thus not spread out in endless profusion, but apparently have 

 a well-knit organization of their own, wherein a limited range of 

 fundamental types spring from a common root. For instance, I 

 have already referred to the type of structures which modern group 

 theory defines. This type has, to be sure, an infinity of exemplifica- 

 tions ; but all these conform to certain simple and fundamental laws. 

 The one theory of groups consequently includes, in a sense, a very 

 large portion of the theory of those conceptual structures which are 

 prominent in modern mathematics. Yet there are systems whose 

 structure is not that of the mathematical group. Their forms, again, 

 vary in ways which we are only just beginning to understand, but 

 which do not seem to exhibit any merely capricious variety. Unity 

 in variety is, then, peculiarly well exhibited in the world of forms. 



IV. 



A few of the problems which such a survey of the morphology 

 of the conceptual world, seems to present, may now be mentioned 

 more in detail. That the forms of possible existence which our 

 thought necessarily recognizes, are indeed limited in number, and 

 depend upon as well as exhibit the necessary constitution of our 

 thought, this philosophers long since came to feel. But the effort 

 to enumerate such fundamental types is greatly hindered by our in- 

 capacity directly to analyze through any introspective process what 

 the logical structures of our concepts may be. For a concept, that 

 is a fashion of thinking, expresses a characteristic way of behavior 



