In Chapter 13, Poem 12 of Attar's Mokhtar Nameh, the poet explores the theme of spiritual restlessness using the metaphor of the 'bird of the heart' (مرغ دل). Because the heart lacks the capacity to contain the profound divine secret, it becomes perpetually agitated, rushing endlessly like the revolving celestial sphere. The poem explains that the heart cannot settle down because it has been displaced from its original spiritual home and has not yet found its true place again.