$5 SENSITIVE MOTIONS. Sect. VIII. 2. ri 



of thefe fenfations, now vividly recur before us by their con- 

 nexion with thefe fenfations themfelves. So the fair fmiling 

 virgin, that excited your love by her prefence, whenever that 

 fenfation recurs, rifes before you in imagination 5 and that with 

 all the pleafmg circumftances, that had before engaged your at- 

 tention. And in fleep, when you dream under the influence of 

 fear, all the robbers, fires, and precipices, that you formerly 

 have feen or heard of, arife before you with terrible vivacity. All 

 thefe fenfual motions, like the mufcular ones above mentioned, 

 are performed with ftrength and velocity in proportion to the 

 energy of the fenfation of pleafure or pain, which excites them, 

 and the quantity of fenforial power. 



II. 1. Many of thefe mufcular motions above defcribed, that 

 are moll frequently excited by our fenfations, are neverthelefs 

 occafionally caufable by volition ; for we can fmile or frown 

 fpontaneoufly, can make water before the quantity or acrimony 

 of the urine produces a difagreeable fenfation, and can volunta- 

 rily mafticate a naufeous drug, or fwallow a bitter draught, 

 though our fenfation would ftrongly diffuade us. 



2. In like manner the fenfual motions, or ideas, that are molt 

 frequently excited by our fenfations, are neverthelefs occafion- 

 ally caufable by volition, as we can fpontaneoully call up our 

 laft night's dream before us, tracing it induftriouily ftep by ftep 

 through all its variety of fcenery and tranfaction ; or can volun- 

 tarily examine or repeat the ideas, that have been excited by our 

 difgult or admiration. 



III. 1. Innumerable trains or tribes of motions are afibciated 

 with thefe fenfitive mufcular motions above mentioned ; as when 

 a drop of water falling into the wind-pipe difagreeably affects 

 tliQ air-vefiels cf the lungs, they are excited into violent action ; 

 and with thefe fenfitive motions are afibciated the actions of the 

 pectoral and intercoftal mufcles, and the diaphragm ; till by 

 their united and repeated fuccefhons the drop is returned 

 through the larinx. The fame occurs when any thing difagree- 

 ably affects the noftrils, or the ftomach, or the uterus ; variety 

 of mufcles are excited by affociation into forcible action, not to 

 be fupprefied by the utmoft efforts of the will ; as in fneezing, 

 vomiting, and parturition. 



2. In like manner with thefe fenfitive fenfual motions, or ideas 

 of imagination, are affociated many other trains or tribes of 

 ideas, which by fomc writers of metaphyfics have been claffed 

 under the terms of refemblance, caufatiouj and contiguity ; and 

 wil more fully treated of hereafter. 



SECT. 



