The earliest dream dictionary that survives today was written by Artemidorus, a Greek who lived in the second century AD/CE.
Artemidorus wrote the Oneirocritica, a five volume work that includes a dream dictionary and an explanation of how to interpret dreams. Some modern dream dictionaries still use interpretations of dream symbols that come from the Oneirocritica. Some of Artemidorus’ interpretations have been used in Christian dream interpretation.
Artemidorus believed that there were two types of dreams – ordinary dreams and “cosmic” dreams.
Priests and seers had cosmic dreams, which were messages from the divine. Priests and seers were already equipped to interpret their own dreams, so Artemidorus focused on interpreting ordinary dreams – the dreams of the common people.
He based his dream interpretations on his own experiences, trying to be as logical as possible.
Artemidorus believed that when you dream, your soul moves and creates images. Your mind takes these images and then uses reason to turn them into dreams.
The Activation Synthesis Theory of Dreams, which was developed by Hobson and McCarley in the 1970s, also states that dreams are caused by your mind trying to make sense of sensations – in this case, random stimuli coming from your brain stem.
Artemidorus believed that the right side represented the masculine and the left side resembled the feminine, because the right side of a person’s body is usually stronger and better developed than the left side.
This idea was expanded upon by some fortunetellers to mean that the right side of something is good luck and the left side is bad luck.