In Section 40 of the Khosrow Nameh, Attar utilizes the daf (frame drum) as an allegory for the spiritual seeker and cosmic harmony. He details the instrument as being constructed from three distinct realms of creation—animal (skin), plant (wood frame), and mineral (metal rings)—representing the synthesis of the physical universe. The striking or slapping of the daf's 'moon-like' face, which yields its resonant cry, symbolizes the trials and spiritual polishing the soul endures to express divine love and reach ecstasy.