ACCOUNT OF BOOKS. 



451- 



casioning a discharge of tears and 

 distortion of countenance, emotions 

 of grief are ever after accompanied 

 by those bodily changes. On the 

 other hand, the first lively pleasure 

 of the infant arising fn)m the fra- 

 grant odour of the mother's milk, 

 which titillates the same ducts and 

 produces a flux of tears, this sensa- 

 tion being likewise accompanied by 

 affection to the mother, tender plea- 

 sure is afterward expressed by a 

 profusion of tears. These examples 

 with others of a like nature, will 

 probably appear fanciful enough to 

 many who admit the force of associ- 

 ation in more decisive instances. 

 As to those actions of brute animals, 

 connected with (heir preservalion 

 and multiplication, which are ge- 

 nerally called instinctive, Dr. D. ad- 

 duces numerous facts to prove that 

 design and experience mingle with 

 many of them, and that brutes are 

 capable of processes like reasoning : 

 but we think that he has by no 

 means shewn either that all, or 

 the most necessary of them, have 

 such an origin. Some of the most 

 decisive examples of instinct, which 

 seem totally inexplicable on other 

 principles, he passes over in a very 

 slight and unsatisfactory manner. 

 Thus that extraordinary and extenit- 

 sive fact of the webs spun by many 

 kinds of caterpillars before their 

 change into the aurelia state, which 

 could not possibly be owing to ex- 

 perience or instruction, since they 

 are creatures of a season which ne- 

 ver knew a parent, is very lamely 

 dismissed, by saying, that ' our ig- 

 norance of their manner of life, and 

 even of the number of their senses, 

 totally precludes us from under- 

 standing the means by which they 

 acquire tins' knowledge.' We pre- 

 «ume that the manner of life of no 



animal is better known than that 

 of a silk worm. 



The catenation of mo'.ions is the 

 subject of sect. 17th. These are 

 produced by irritations, sensations, 

 or volitions. Their cause, probably, 

 isthe property of^animal motions to 

 proceed some time after they are 

 excited, though the exciting object 

 be removed. The laws of these 

 catenations are laid down and ex- 

 emplified in this section with much 

 ingenuity. One of the principal 

 exemplifications is drawn from the 

 process of learning music. 



S. 18. describes sleep and all its 

 phenomena ; and much acuteness 

 is displayed by the author, in shew- 

 ing how the suspension of the power 

 of volition, and the increase of 

 energy in the other sensorial powers, 

 owing to the consequent accumula- 

 tion of the spirit of animation, ope- 

 rate in producing all the varied 

 and wonderful circumstances which 

 occur during that state of the 

 body 



Reverie is the subject of sect. ig. 

 It is made to include somnambulism, ^ 

 and to partake of epilepsy or cata- 

 lepsy. Complete reverie is charac- 

 terized by the continuance of all the 

 motions but those which are ex- 

 cited by the stimuli of external ob- 

 jects, 



S. 20. treats of vertigo. It is 

 first observed that, as we determine 

 oar perpendicularity of position by 

 the apparent motions of objects, 

 whatever prevents or disorders our 

 judgment in this respect makes us 

 liable to fall, or induces vertigo. 

 A 1^0, when irritative motions or' 

 sounds, which usually are unnoticed 

 by the mind, becomc,from any cause, 

 the objects of sensation or attention, 

 the confusion thus made in the or- 

 dinary catenations or circles of ideas 



excites 



