Dreams were most important

From unknown times people treated dreams as most important to them. Dreams have made people to wonder, fear and enjoyment too. Priest made them sacred, when dead ones appeared in their dreams, people feared,

Dream promised victory

The sign of a Christian cross appeared to Emperor Constantine of Rome in a dream that promised his victory in the battle.

“Constantine had probably experienced his great "in hoc signo vinces" vision in 312 before his victory at the Milvian Bridge battle. The story goes that Constantine had a vision of those words upon a Christian cross and that this vision prompted Constantine to pledge to convert if he actually did win the battle. Since he was the victor, the vision led to his conversion to Christianity, ultimately.”
http://ancienthistory.about.com/cs/people/p/constantine.htm