"Transition between levels of consciousness are often represented as the crossing of a barrier, such as a door or gate protected by guardians or by magic. The key to the gate may be a magical formula, or knowledge of a secret doctrine. In essence, the key is self-knowledge. The gate of Gehenna, the first of the nine Moslem hells, is approached by Mohammad on his Night journey. Before the flame-barrier stand the Archangel Gabriel and Malik, Prince of Darkness.

   The alchemist who has followed the hermetic river to its source approaches the entrance to the Philosopher's Rose Garden. He must open the locks of the gate with the Twelfth Key of the royal art; that is, he must have attained the appropriate level of esoteric knowledge,

   In a scene from the Egyptian Book of the Dead, the traveller before the gate is Anhai, priestess and  musician of the sun god Amen-Ra. The gates are guarded by gods, half human and half animal in form."
 Stanislav and Christina Grof, Beyond Death, The gates of consciousness, Thames and Hudson, p.36 –37, pp. 50.

Mohammad's Night journey, from an illuminated ms., Miraj Nameh, East Turkey, 15th century. 

 The Philosopher's Rose Garden, engraving from Michael Maier, Atalanta fugiens, 1617. Papyrus of Anhai, Egypt, 20-21^st Dynasty.)