442 THE ANIMAL FUNCTIONS. [ch. v, 



SECTION II. IS THE FACULTY OF THOUGHT THE SPECIAL PRO- 

 PERTY OF THE MIND, OR IS IT NECESSARY TO THOUGHT THAT 

 THE MIND USE THE BRAIN AS AN INSTRUMENT? 



Many pliilosophers and physicians have asserted, that the 

 mind alone thinks, and the body takes no part in that opera- 

 tion ; on the other hand, some have maintained that thought 

 itself is a faculty belonging to matter, and denied that the soul 

 is immaterial ; others, thinking that both were far wide of the 

 truth, have imagined they could set the matter at rest by 

 stating that certain operations of the thinking faculty are partly 

 owing to the body, as memory, for example, but that others 

 are performed by the mind alone, and independently of 

 the body. 



If we consult daily observation, we learn that the faculty of 

 thought is subject to various viscissitudes, and corresponds 

 closely with the condition of the brain. The foetus hid in the 

 uterus of its mother, neither sees, nor hears, nor tastes, nor 

 smells, nor scarcely feels the fluids that surround it. Thus 

 destitute of ideas, it neither judges nor imagines, nor remem- 

 bers. On emerging into light, the fcetus, indeed, begins to 

 perceive objects through the organs of the external senses, but 

 it cannot as yet correctly judge between ideas, and quickly 

 forgets its perceptions, for the semi-fluid brain seems unfit to 

 retain them, and consequently, we remember nothing of that 

 period. The same mind in the youth, with a firmer and more 

 condensed brain, retains ideas readily and with remarkable 

 facility, and is endowed with somewhat of the power of judg- 

 ment as to serious matters, although but feebly. In manhood, 

 the solids generally, and therewith the brain, being consolidated, 

 it commits new ideas to memory, and retains them with less 

 facility, but enjoys by so much the more a riper judgment. In 

 old age, new ideas are retained with still greater difficulty, but 

 the old being indurated, as it were, like the brain, pertinaciously 

 adhere to it ; yet some aged persons lose even these, and 

 return to the state almost of plants, oblivious of the world, 

 their friends, and themselves.^ The mental endowments diff"er 



^ Haller, in his notes to the * Prselect. Instit. Med.' of Boerhaave, and in his 

 ' Elem. Phys.,' torn, v, p. 538. 



