"One of the created phenomena is the dream."

"Indeed, O Brother, if we ponder each created thing, we shall witness a myriad perfect wisdoms and learn a myriad new and wondrous truths. One of the created phenomena is the dream. Behold how many secrets are deposited therein, how many wisdoms treasured up, how many worlds concealed. Observe, how thou art asleep in a dwelling, and its doors are barred; on a sudden thou findest thyself in a far-off city, which thou enterest without moving thy feet or wearying thy body; without using thine eyes, thou seest; without taxing thine ears, thou hearest; without a tongue, thou speakest. And perchance when ten years are gone, thou wilt witness in the outer world the very things thou hast dreamed tonight.

Now there are many wisdoms to ponder in the dream, which none but the people of this Valley (The Valley of Wonderment) can comprehend in their true elements. First, what is this world, where without eye and ear and hand and tongue a man puts all of these to use? Second, how is it that in the outer world thou seest today the effect of a dream, when thou didst vision it in the world of sleep some ten years past? Consider the difference between these two worlds and the mysteries which they conceal, that thou mayest attain to divine confirmations and heavenly discoveries and enter the regions of holiness.

God, the Exalted, hath placed these signs in men, to the end that philosophers may not deny the mysteries of the life beyond nor belittle that which hath been promised them..."

-Bahá'u'lláh, The Seven Valleys And the Four Valleys, pp. 32-33