In Chapter 18, Poem 19 of Attar's Mokhtar Nameh, the 'bird of the heart' (مرغ دل) is characterized as a mad lover consumed by the passion of love. The poem portrays the soul's boundless and restless pursuit, flying across a hundred thousand worlds in every moment yet never finding a place to alight or rest. This imagery highlights the insatiable nature of spiritual yearning and the perpetual, unsettled motion of the seeker's soul, which can find no ultimate contentment in any single realm or worldly station.