_Estimate of Time._--Nothing has seemed to some writers more mysterious than the entire disproportion between the _real_ and _apparent_ time of a dream. I refer to the fact that our dreams occupy frequently such very minute portions of time, while they seem to us to stretch over such long continued periods. An instance is related of an officer confined in the prisons of the French Revolution, who was awakened by the call of the sentry changing guard, fell asleep again, witnessed, as he supposed, a very long and very horrible procession of armed and bloody warriors, defiling on horseback down a certain street of Paris, occupying some hours in their passage, then awoke in terror in season to hear distinctly the response of the sentry to the challenge given before the dream began. The mind in such cases, say some, operates more rapidly than at other times. There is no evidence of that. Mr. Stewart has suggested, I think, the right explanation. As our dreams seem to us real, and we have no means of estimating time otherwise than by the apparent succession of events, the conceptions of the brain, that is, our dreams, seem to us to take up just so much time in passing as the _events themselves_ would occupy were they real. This is perfectly a natural result, and it fully accounts for the apparent anomaly in question. _Prophetic Aspect._--Are dreams sometimes _prophetic_, and how are such to be accounted for? Cicero narrates a remarkable instance of what would seem to be a prophetic dream. I refer to the account of the two Arcadians who came to Megara and occupied different lodgings. The one imploring help, then murdered, and informing his comrade that his body would be taken out of the city early in the morning, by a certain gate, in a covered wagon. Agitated by the dream, the other repairs at the designed time to the appointed place, meets the wagon, discovers the body, arrests the murderer, and delivers him to justice. _Other Instances of the like Nature._--Another instance, perhaps equally striking, is narrated in the London _Times_. A Mr. Williams, residing in Cornwall, dreamed thrice in the same night that he saw the Chancellor of England killed, in the vestibule of the House of Commons. The dream so deeply impressed him that he narrated it to several of his acquaintance. It was subsequently ascertained that on the evening of that day the Chancellor, Mr. Perceval, was assassinated according to the dream. Now, this was certainly a remarkable coincidence. Was it any thing more? Was it merely an accidental thing--a matter of chance--that the dream should occur as it did, and should tally so closely with the facts? But these are not singular instances. Many such are on record.