Quote from : Buddha: A Story of Enlightenment Book

Asita had been raised on this knowledge. He knew also that all these planes merged into each other like wet dyed cloths hung too close on the line, the blue bleeding into the red, the red into the saffron yellow. Lokas were apart and together at the same time. Demons could move among humans, and often did. The re-verse, a mortal visiting the demon loka, was much rarer.