The history of man knows these certain people who are believed to be mediators between the known world and the supernatural. They've carried different names - witch, priest, magician, oracle - just to name a few. Philosophy, as well, has tracks of those two realms connecting, for example through the noplatonic scholar Plotinus (third century A.D). Those named sources have meditation or a sort of inner focusing as the source that makes the connection possible.
Now, i find fiction to be much more interesting because it brings a variety of artifacts into play. To name some, i recall the fairy tales Pied Piper of Hameln and Jack And The Beanstalk or love-in-idleness magical juice in A Midsummer's Night Dream (yes, even the magical creatures couldn't escape the use of a little 'help'). The idea of 'magical artifacts' seems to be hot even in modern hardcore science fiction when i think of Matrix (where the supernatural realm was offered to Neo in the form of the red pill).
This brings me to my newest painting where the clarion call summons fourth spirit-like creatures. I listen to a lot of music when i paint, so it seemed to be suitable to bring the idea of sound into play. Also, sound, in any form visualized, gives a painting a level of dynamics, that's few discussed so far. The truth is, that a person watching a painting with hints to sound (or smell, or taste), starts to generate the sensory experience in his/her mind, this way co-creating the scene on an emotional level.