Al-Khidr, a character generally unknown in Western culture, occupies a very important place in the popular and mystical knowledge of the countries of the Islamic rhizome, although his origins go back to ancestral times.

Al-Khidr, literally "the Verdant One" or "the Green One", inhabits the in-between world, the no-man's land, the fine interstice between the real and the unreal, life and death, sleep and wakefulness... this place is called Barzakh, the isthmus. Where he passes, everything greens up, even the tracks of his footsteps are immediately covered with grass.