Avicen makes the cause of dreams to be an ultimate intelligence moving the moon in the midst of that light with which the fancies of men are illuminated while they sleep. Aristotle refers the cause of them to common sense, but placed in the fancy. Averroes, an Arabian physician, places it in the imagination; Democritus ascribes it to little images, or representations, separated from the things themselves; Plato among the specific and concrete notions of the soul; Albertus to the superior influences, which continually flow from the sky, through many specific channels. Some physicians attribute the cause of dreams to vapours and humours, and the affections and cares of persons predominant when awake; for, say they, by reason of the abundance of vapours, which are exhaled in consequence of immoderate feeding, the brain is so stuffed by it, that monsters and strange chimera are formed, of which the most inordinate eaters and drinkers furnish us with sufficient instances. Some dreams, they assert, are governed partly by the temperature of the body, and partly by the humour which mostly abounds in it; to which may be added the apprehensions which have preceded the day before; and which are often remarked in dogs, and other animals, which bark and make a noise in their sleep. Dreams, they observe, proceed from the humours and temperature of the body; we see the choleric dreams of fire, combats, yellow colours, etc. the phlegmatic of water baths, of sailing on the sea; the melancholies of thick fumes, deserts, fantasies, hideous faces, etc. they that have the hinder part of their brain clogged, with viscous humours, called by physicians Ephialtes incubus, dream that they are suffocated. And those who have the orifice of their stomach loaded with malignant humours, are affrighted with strange visions, by reason of those venemous vapours that mount to the brain and distemper it. POETICAL ILLUSTRATIONS OF THE EFFECTS OF THE IMAGINATION IN DREAMS. Were we to enter more profoundly into the mysterious phenomena of dreams, our present lucubrations might become too abstruse; and, after all, no philosophical nor satisfactory account can be given of them. Such of our readers therefore, as may wish for a more minute inquiry into the opinions above stated, we beg leave to refer to the respective authors whom we have already quoted. The reader, who is fond to find amusement even in a serious subject, from the scenes of nocturnal imagination, will be glad, perhaps for a moment, to be transported into the regions of poetic fancy. And here we find that the fancy is not more sportive in dreams, than are the poets in their descriptions of her nocturnal vagaries. On the effects of the imagination in dreams, the following effusion, put into the mouth of the volatile Mercurio, is an admirable illustration:--