I think some dreams, maybe not all, but some, are not entirely "in the mind". I think that some of them transport part of your essence, or energy of some sort uniquely "you" to other places, other realms, perhaps other dimensions, for real... albeit temporarily.
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“Trouble rather the tiger in his lair than the sage among his books. For to you kingdoms and their armies are things mighty and enduring, but to him they are but toys of the moment, to be overturned with the flick of a finger.”
― Gordon R. Dickson, Tactics of Mistake
― Gordon R. Dickson, Tactics of Mistake