In Attar's 'The Speech of a Sufi Man Concerning His State' from The Conference of the Birds, the material world is allegorically compared to a furnace (گلخن - gulkhan). The Sufi speaker describes his state of being trapped within this dangerous furnace, surviving only by keeping a low profile. The central theme of the poem is that true cheerfulness or happiness (خوش دلی) is fundamentally absent in the worldly realm. The ego and worldly attachments act like a destructive fire, leaving no possibility for genuine peace of heart.