

PHYSIOLOGY. 147 



awake and when it is asleep. The states of the brain corre- 

 sponding to this difference, I have termed the states of excite- 

 ment and collapse. I say, that in sleep the mind does not per- 

 ceive its usual or ordinary train of thinking which is necessary 

 to sound judgment. We have, in dreaming, false imagination, 

 incoherence, and inconsistency ; but these are all the marks of de- 

 lirium. The passage from waking to sleep also, or from sleeping 

 to waking, is usually gradual. Thus, when I find my friend just 

 now asleep, his ears are open, and I get his eyes open ; some 

 time elapses before I can make him recollect who I am, or that 

 I have made an appointment with him : he does not know me, 

 or the purpose of our meeting together ; but this is a matter of 

 a few moments only, and is discussed by establishing the total 

 excitement of the brain ; and here there is no organic affec- 

 tion, but only one portion of the brain is in a state of col- 

 lapse, while another portion of it is excited. This I cannot il- 

 lustrate better than by the following very elegant account of 

 the phenomena of sleep from Bailer's Prim. Lin. 580. 

 * Nocte redeunte sensim torpor percipitur in musculis longis, 

 ineptitudo ad cogitationes severiores, amor quietis in animo et 

 corpore. Tune peculiariter vires corpus erectum tenentes la- 

 borant, et oculi nolenti clauduntur, et maxilla inferior pendet, 

 et oscitationis necessitas ingruit, et caput antrorsum nutat, et 

 objectorum externorum actiones minus nos adficiunt, et denique 

 turbantur ideae, et cogitationes, et delirium succedit, a quo in 

 somnum non satis notus transitus est, quod tamen somnum 

 semper praecedit.' Various theories of dreaming have been 

 given ; some have supposed that it depends upon circum- 

 stances of our own bodies ; others, that it is owing to the 

 influence of spirits without us. With regard to the possibil- 

 ity of this last supposition I will not determine, but certain- 

 ly, for the most part, it is owing to the state of our bodies ; 

 and we say with Haller, that it is in consequence of some 

 stimulus that is more powerful in sleep, while from the ordi- 

 nary causes of sleep, the collapse is very nearly entire, but 

 the force of the stimulus can keep up the excitement in some 

 portion of the brain, which runs more or less into some train of 

 thought ; and so it is a dream, a delirium, and no other ex- 

 planation is necessary to say why that may be in different de- 



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