CH. III.] EXTERNAL SENSATIONAL ACTIONS. 97 



bodies, that are susceptible of the sentient actions just described, 

 in virtue of their nerves. We will now consider, in what me- 

 chanical machines, and by what laws, the different conceptive 

 forces of the soul manifest their actions externally to the brain, 

 in animal bodies, and in what these consist. We will begin 

 with the sensational perception and desires {76, 89), and 

 afterwards consider those of the intellect. 



The Actions of External Sensations through the Nerves in the 

 Mechanical Machines. 



181. It is not so easy a task as it appears, to discover the 

 direct sentient actions of external sensations in the mechanical 

 machines. All those produced by an irritation of a nerve, 

 or by the external impression transmitted along the nerve, or 

 even by its propagation to the brain, or deflection thence, are 

 its animal actions ; but none is a sentient action of an external 

 sensation (98), unless it belong to the class caused in the me- 

 chanical machines by an external sensation, or by the material 

 cerebral sensation acting as an impression in the brain (121, 97). 

 All movements, consequently, in the mechanical machines, 

 which the external impression excites by its own proper animal 

 forces, before it has formed external sensations in the brain, 

 and all that it produces in other nerves and mechanical ma- 

 chines in its course to the brain, in virtue of the motive force 

 peculiar to itself, cannot be considered as the sentient actions 

 of external sensations, even although they be also developed 

 by the external sensations of the external impressions. All 

 the sentient actions produced in the mechanical machines 

 through the nerves only, of imaginations, foreseeings, sensa- 

 tional instincts, emotions, intellectual conceptions, or desires and 

 aversions of the will, excited in the mind by external sensations, 

 are not true direct sentient actions of the external sensations, 

 although all the material ideas of the conceptions produced 

 by the latter are their indirect sentient actions (97, 98). 



182. Hitherto, these actions (altogether distinct) have been 

 indiscriminately considered as direct sentient actions of external 

 sensations, and so the physiological doctrines of external sen- 

 sations have been sadly confused. It is, consequently, of im- 



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