M4:742 — آتش عشق از نوا‌ها گشت تیز / آن چنان که آتش آن جوزریز

This couplet appears in a section discussing the power of samaʿ (spiritual music or audition) for lovers and seekers. Rumi has just explained that samaʿ is the 'food of lovers' because it evokes the memory of the primordial gathering of souls in Paradise, before their descent into the physical world. This memory, though faint, is a 'desire for reunion' (khiyāl-e ijtimaʿ).

Here, Rumi uses a vivid, earthy metaphor to describe the effect of samaʿ. Just as a physical fire can make a walnut 'keen' or 'sharp' (i.e., crack it open to reveal its kernel), so too does the 'fire of love' (ātash-e ʿishq) become 'keen' or intensified by these melodies. The music acts as a catalyst, making the inner spiritual fire more potent and effective. The cracking of the walnut can be seen as a metaphor for the breaking open of the ego or the unveiling of inner spiritual truths, facilitated by the transformative power of divine love awakened through samaʿ.