Human beings have never been indifferent to their dreams. But in different epochs concepts of their essence, origin and significance have varied.  The first data comes from Mesopotamia, from the epic of Gilgamesh. The epic relates the heroic deeds of the ruler of Uruk. It is the oldest known record of a historic person who lived around 2700 B.C. At the same time it contains the most ancient documented dreams. In the epic the dreams serve to announce the plans of the Gods to people, so that they can act accordingly.  Enkidu and Gilgamesh are on their way to kill the "bloodsucker" Humbaba. In order to find out whether they will be successful they pray to the Sun God for a dream. The next night Gilgamesh has a dream, of which Enkidu says:  This dream will make you well.  Brother, that vision you saw is rich  for on that mountain top  we can capture Humbaba and  hurl his earthly form from  towering cliffs through sky to  earth, making his shape  as flat and wide as it is round and high

Tablet V of the Epic of Gilgamesh