CHAP. XXIX.] SPEECH AND THOUGHT. 615 



generation, have been available in the case of man for 

 the building up of that great department of human 

 knowledge known as Objective Psychology. 



Our aims now, however, are different from what they 

 were in the earlier chapters, when considering the mental 

 processes of lower animals. We were then principally 

 concerned with the endeavour to ascertain something as 

 to the nature of these mental processes, in order to 

 learn whether, or to what extent, they were similar to 

 those of Man. It was necessary to ascertain, in fact, 

 whether the general similarity in structure of their Ner- 

 vous System, carried with it a general similarity in mode 

 of action. But now we are not concerned so much with 

 the estimation of the nature and extent of Man's mental 

 powers, as with (a) the nature and order of the processes 

 involved in Thought and Intellectual Expression ; and 

 (I)) with the endeavour to refer some of these processes to 

 the activity of definite parts of the Brain. These, in fact, 

 are the final questions needing consideration, in order to 

 complete our necessarily imperfect sketch of what is at 

 present known concerning 'the Brain as an organ of Mind.' 



In the first of these analytical studies we have briefly 

 to consider some of the more typical of the various defects 

 in Perception, Verbal Memory, Thought, and Intellectual 

 Expression (either by Speech or Writing), which have 

 been observed as results of disease or injury in different 

 parts of the Cerebral Hemispheres. 



The great importance of the due activity of the 

 Auditory and Visual Preceptive Centres, and the absolute 

 dependence of the great bulk of our intellectual percep- 

 tions, of our memory of words, and of our powers of 

 thought, as well as of intellectual expression, upon the 

 functional integrity and proper inter-action of these parts 



