270 



ON SLEEP, DRBAMINt,'' 



mantled, but run away with by foreign compulsion, and the work of a 

 demoniacal possession. 



The difficulties into which such an explication throws its adherients, are 

 incalculable. Let us confine ourselves to one more example. There can 

 be no doubt that other animals have their dreams as well as man ; and that 

 they have them as vigorous and as lively. Every one has beheld hia 

 favourite dog, while asleep by the fire-side in the winter season, violently 

 stretching out his hmbs, howhng aloud, and at times starting abruptly, be- 

 neath the train of images of which his dream is composed. In what man- 

 ner will such philosophers account for these various phasnomena ? Is dream- 

 ing a natural operation, or are good and evil spirits the natural attendants 

 upon dogs and cats, as well as upon mankind ? The one or the other of 

 these conclusions must follow ; and there can be no difficulty in deter- 

 mining which of them will possess the general suffrage. 



That dreams, like every other concurrence in nature, may occasionally 

 become the medium of some providential suggestion, or supernatural com- 

 munication, I am by no means disposed to deny. That they have been so 

 employed in former times is unquestionable ; and that they have been so 

 employed occasionally among all nations in former times, is highly proba- 

 ble ; and the peculiar hveliness with which the trains of our dreaming ideas 

 are usually excited, and from a cause virhich \ shall presently endeavour to 

 explain, seems to point out such a mode of communication as peculiarly 

 eligible. But I am at present attending to the natural phasnomena alone, 

 and can by no means enter into a consideration of such foreign interference, 

 which, as it certainly has been, may still therefore be, for all we can prove 

 to the contrary, occasionally introduced into them. 



In what may be called our own times, there are many valuable writers 

 who have turned their attention to this curious subject, and who concur in 

 the two following important positions. First, that the faculty, or at least 

 the action of the will is suspended during the influence of sleep : and, se- 

 condly, that in consequence of this suspension or discontinuance, the trains 

 of ideas which persevere in rushing over the mind, are produced and cate- 

 nated by that general habit of association which catenates them whilst we 

 are awake. The power of the will, it is contended, is not necessary to the 

 existence of ideas, which, therefore, may continue whilst such power is in 

 a state of abeyance ; but which, if they continue at all, must take the 

 general order and succession imprinted upon them by the law of associa- 

 tion, excepting in cases in which such law is broken in upon by a variety of 

 incidental circumstances, as uneasiness arising from a surcharged stomaclj^ 

 or other bodily sensations. 



Such are the two fundamental principles upon which the theories of 

 Hartley, Darwin, and Dugald Stewart are respectively built ; and whichfl 

 in various -ways and with almost equal ingenuity, they seem very satisfac- 

 torily to have established. But there is still a very important question, 

 and which, indeed, constitutes the chief difficulty of the subject, and that 

 which none of them have attempted to answer, or at least have satisfied 

 themselves upon while making such attempt. I mean, whence comes it 

 to pass that ideas can at all exist in the brain during sleep, or that all the 

 internal senses are not as much locked up as the external senses, and the 

 faculty of the will ? 



In the course of the present lecture it will be my endeavour to account 

 for this most curious phaenomenon. But we must first follow up, in the 

 series in which they appear to arise, the train of circumstances which a<j- 



