In Chapter 18, Poem 8 of Attar's Mokhtar Nameh, the poet uses the metaphor of the 'bird of the heart' (مرغ دل) trapped within the physical cosmos, described as the 'egg of the seven heavens' (بیضهٔ هفت آسمان). The poem emphasizes that the soul cannot achieve true spiritual flight by merely wandering the physical world. Instead, the seeker must completely shatter the limitations of the material universe—breaking the cosmic egg—to allow the spiritual heart to transcend physical boundaries and ascend to the divine.