In Attar's Asrar Nameh, the allegory of the slave carrying a covered tray illustrates the inaccessibility of divine and cosmic secrets. When asked what is on the tray, the slave explains that if the contents were meant to be known, they would not be covered. This metaphor emphasizes human limitations in comprehending the hidden workings of the universe and divine will, comparing the covered tray to the profound mysteries concealed beneath the 'seven veils' of the heavens.