EXPLANATION OF THE DIAGRAM. 63 



CHAPTEE V. 



Explanation of the Diageam. 



We have now sufficiently considered the sundry first prin- 

 ciples and preliminary questions which lie at the threshold of 

 our subject proper. It seemed to me desirable to dispose of 

 these principles and questions before we enter upon our 

 attempt at tracing the probable history of Mental Evolution. 

 But now that these first principles and preliminary questions 

 have been disposed of, so far as their nature renders possible, 

 the way is as clear as it can be for us to pursue our enquiry 

 concerning the Genesis of ]\Iind. In order to give definition 

 to the somewhat laborious investigation on which we are thus 

 about to embark, I have thought it a good plan to draw a 

 diagram or map of the probable development of Mind from 

 its first beginnings in protoplasmic life up to its culmination 

 in the brain of civilized man. The diaOTam embodies the 



o 



results of my analysis throughout, and will therefore be 

 repeatedly alluded to in the course of that analysis — i.e., 

 throughout the present and also my future work. I may 

 therefore begin by explaining the plan of this diagram. 



The diagram, as I have just said, is intended to represent 

 in one view the whole course of mental evolution, supposing, 

 in accordance with our original hypothesis, such evolution to 

 ^ave taken place. Being a condensed epitome of the results 

 of my analysis, it is in all its parts carefully drawn to a 

 scale, the ascending grades or levels of which are e\^erywhere 

 determined by the evidence which I shall have to adduce. 

 The diagram is therefore not so much the product of my indi- 

 vidual imagination, as it is a summary of all the facts which 

 science has been able so far to furnisli upon the subject ; and 

 although it is no doubt true that the progress of science may 

 affect the diagi-am to the extent of altering some of its details, 

 I feel confident that the general structure of our knowledge 

 concerning the evolution of mind is now suthciently coherent 



