In Section 18 of the Hadiqat al-Haqiqah, Sana'i employs the metaphor of 'eating clay' (گل خوردن) to represent human attachment to base, materialistic desires. He warns that just as eating clay physically causes a person's face to turn pale and yellow, spiritual 'clay-eating' deprives the heart of divine light and ultimately leads to spiritual death. To truly nurture the heart, the seeker must abandon this vile nourishment and instead drink the 'wine of submission' (شراب مفرح تسلیم) to the divine will. This imagery of worldly pursuits as 'eating clay' became a recurrent motif in later Sufi literature to illustrate the soul's degradation through earthly attachments.