This verse is cited to elaborate on the symbolism of the reed (نی) and the concept of humanity's existential hollowness. Dr. Soroush explains that Rumi here explicitly acknowledges our essential non-being (fana) and dependence on God. We are like lions, but merely lions depicted on a banner (شیر عَلم). We appear powerful, but our "attack"—our action—is not self-generated. It is caused by an unseen force, the "wind" (باد), which represents the divine power that animates us. [d1-s4]
The scholar immediately reinforces this interpretation by quoting the subsequent verse: "Their attack is visible, but the wind is unseen / May my soul be sacrificed for that which is unseen." This illustrates the principle of tawhid al-af'al (the unity of acts), which attributes all actions to God as the true agent. [d1-s4]
This metaphor is consistent with others Rumi uses to convey the same idea, such as humans being a reed whose melody comes from the blower ("ما چو ناییم و نوا در ما ز توست") or chess pieces moved by a player. In all these images, the human is a hollow instrument or a passive figure whose being and action derive from another source. We are fundamentally "non-beings" (نیست) to whom God has granted the "pleasure of existence" (لذت هستی). [d1-s4]