The Peripatetics represented dreams as arising from a presaging faculty of the mind; other sects imagined that they were suggestions of daemons. Democritus and Lucretius looked upon them as spectres and _simulacra_ of corporeal things, emitted from them, floating in the air, and assailing the soul. A modern writer, Andrew Baxter, entertained a notion somewhat similar, and imagined that dreams were prompted by separate immaterial beings, or spirits, who had access to the sleeper's brain with the faculty of inspiring him with various ideas. Burton divides dreams into natural, divine, and daemoniacal; and he defines sleep, after Scaliger, as "the rest or binding of the outward senses, and of the common sense, for the preservation of body and soul." Gradually released from the trammels of superstition, modern philosophers have sought for more plausible explanations of the nature and causes of dreams, but perhaps without having attained a greater degree of certainty in this difficult question than our bewildered ancestors. Wolfius is of opinion that every dream originates in some sensation, yet the independent energies of the mind are sufficiently displayed in the preservation of the continued phantasms of the imagination. He maintains that none of these phantasms can prevail unless they arise from this previous sensation. De Formey is of the same opinion, and conceives that dreams are supernatural when not produced by these sensations. But of what nature are these sensations? Are they corporeal impressions received prior to sleep, and the continuances of reflection, or are they the children of an idle brain? Although it is not easy to trace an affinity between the subjects of our dreams and our previous train of thought, yet it is more than probable that dreams are excited by impressions experienced in our waking moments, and retransmitted to the sensorium, however difficult it may be to link the connexion of our ideas, and trace their imperceptible catenation. Moreover, there does not exist a necessary and regular association in the state of mind that succeeds any particular impressions. These impressions only predispose the mind to certain ideas, which act upon it with more or less subsequent energy, and with more or less irregularity, according to the condition in which the predisposing causes have left it. It has been observed that we seldom dream of the objects of our love or our antipathies. Such dreams may not be the natural results of such sentiments. We may fondly love a woman, and in our dreams transfer this soft sensation of fondness to another individual,--to a dog that fondles us, or any other pleasing object. We may have experienced fear--in a storm at sea; yet we may not dream of being tossed about in a boat, but of being mounted upon a runaway horse who hurries us to destruction, or of flying from a falling avalanche. Our mind had been predisposed by fear to receive