CH. II.] MATERIAL IDEAS. 25 



at every act of mind,^ whether it be a sensation, imagination, 

 desire, reflection, or conclusion, there is produced in it a cer- 

 tain animal movement, necessary thereto, without which the 

 act of thought [Vorstellung] can neither arise nor continue, 

 and with which it infallibly arises and continues. This animal- 

 sentient force is peculiar to the brain, and is the property of 

 no other portion of the nervous system^ because in none other 

 except in the brain does an animal movement develope per- 

 ceptions (10). The medullary matter of the brain can also, with 

 propriety, be designated as the only instrument of the sentient 

 force, for it is through its animal movements that the mind 

 puts its force into action, and maintains it, and without which, 

 it would absolutely remain inactive. Philosophers have already 

 introduced the phrase, material ideas, to express those move- 

 ments in the brain that are necessarily connected with each 

 act of thought. (Baumgarten's Metaphysics, § 416.) A psy- 

 chological materialist considers these material ideas as the ideas 

 of the mind itself. But since it must be firmly maintained, 

 that the thinking faculty is an immaterial substance [Substanz), 

 it cannot certainly be granted that these material changes in 

 the brain are really the ideas themselves ; but since the two 

 are inseparately connected with each other, and the mind never 

 acts, nor can act, in animals, without these movements, it is 

 fully established that every act of thought presupposes and 

 causes a movement in the brain (material idea), and every such 

 movement in the brain presupposes and causes a conception in 

 the mind ; that the same or a similar conception excites the 

 same or a similar material idea, and that the same or a similar 

 material idea excites the same or a similar conception in the 

 mind ; that when there are no conceptions excited in the mind, 

 there are no material ideas, although probably similar movements 

 may take place in the brain; that when no material ideas take 

 place in the brain, no conceptions come into real existence in the 

 mind (112) ; and that the perfection or imperfection of the mental 



' The phrase Vorstellung der Seele is here translated act of mind. Vorstellung is 

 of very frequent occurrence throughout the work, and is ordinarily translated con- 

 ception. The reader must, however, bear in mind, that the term " conception " does 

 not so exactly express the author's meaning as " act of mind," inasmuch as Vorstel- 

 lung is applied to signify sensation, perception, and thought generally, — in short, 

 evert/ mental operation ; whereas conception has a more limited application. No other 

 word could be found, however, more nearly expressing the author's meaning. — Ed. 



