How Did Dreams Come to Be?

The idea that dreams could give us knowledge straight from the divine goes right back as far as Homer. It became a major concern later on when philosophers began to consider dreams in terms of whether they were legit sources of true knowledge or not. There's some late evidence that dreams were very important to the Pythagoreans, which would make theirs probably the first attempt to deal with dreams philosophically or proto-philosophically. But our evidence is very late and there are strong reasons for not reading this later evidence back onto the early Pythagorean movement - although it does tell us a lot about the Roman world where it originates.