41^ 



ON Al^CIENT AND MODERN SKEPTICS. 



they supply us with, and what they themselves derive from the world be« 

 fore them ; that the mind is nothing more than the general result of their 

 action ; and that with them it begins, and with them it ceases. 



To Hobbes succeeded Spinosa, who was born in the very same year 

 with Locke, and who carried forward the crusade of matter against mind, 

 to so illimitable a career, that he made the world, the human senses, the 

 human soul, and the Deity himself, matter and nothing else : all one com- 

 mon material being ; no part of which can or ever could exist otherwise 

 than as it is, and consequently every part of which is equally the creature 

 and the Creator. 



In the midst of these indiscriminate assaults, appeared Hartley ; who^e' 

 learning, benevolence, and piety, entitle his memory to be held in venera- 

 tion by every good man. He strenuously contended for the existence of 

 mind and matter as distinct principles ; and conceived it was in his power 

 to settle the general controversy, by showing what Locke had failed to do, 

 or rather what he had too much modesty to attempt ; the direct means by 

 which the external senses, and consequently the external world, operates 

 upon the mind. And hence arose the well known and at one time highly 

 popular hypothesis of the association of ideas. It was conceived by Dr. 

 Hartley that the nervous fibrils, which form the medium of communica- 

 tion between the external senses and the brain or sensory, are solid and 

 elastic capillaments ; that on every impression of objects upon the senses 

 the nervous chord, immediately connected with the sense, vibrates through 

 its whole length and communicates the vibration to the substance of the 

 brain, and particularly to its central region, which is the seat of sensation, 

 leaving upon every communication a mark or vestige of itself ; which 

 produces a sensation, and excites its correspondent perception or idea. 

 The more frequently these vibrations are renewed, or the more vigorously 

 they are impressed, the stronger will be the vestiges or ideas they induce ; 

 and as, in every instance, they occasion vibratiuncles, or miniature vibra- 

 tions, through the substance of the brain itself, a foundation is hereby laid 

 for a series of slighter vestiges, sensations, and ideas after the primary 

 vibrations have ceased to act. And hence originate the faculties of jne- 

 mory and imagination. And as any order of vibrations, by being associated 

 together a certain number of times, obtain a habit of mutual influence, any 

 single sensation or single idea belonging to such order acquires a power 

 of calling the whole train into action, either synchronously or successively, 

 whenever called into action itself. 1 



Now according to this system the brain of man is a direct sensitive 

 violin, consisting of musical strings, whose tones go off in thirds, fifths,-' 

 and eighths, as regularly as in a common fiddle, through the whole extent 

 of its diapason ; and the orator who understands his art, may be said, 

 without a figure, to play skilfully upon the brains of his auditors. Thq 

 hypothesis, however, is ingenious and elegant, and has furnished us with ; 

 a variety of detached hints of great value ; but it labours under the follow- 

 ing fatal objections. First, the nervous fibres have little or no elasticity 

 belonging to them, less so perhaps than any other animal fibres whatever ; 

 and next, while it supposes a soul distinct from the brain, it leaves it no 

 office to perform : for the medullary vibrations are not merely causes of 

 sensations, ideas, and associations, but in fact the sources of reason, belief, 

 imagination, mental passion, and all other intellectual operations whatever. 



Admitting, therefore, the full extent of this hypothesis, still it gives us 

 no information about the nature of the mind and its proper functions : and 



