M4:66 — در زمانه هیچ زهر و قند نیست / که یکی را پا دگر را بند نیست

This couplet serves as the philosophical core of the story of the lover and the night watchman. The lover, fleeing from what he perceives as a threat (the watchman), stumbles into the garden of his beloved. The apparent evil turns out to be the cause of his greatest joy. Rumi uses this narrative to pivot to a wider metaphysical point: the relativity of good and evil.

The images of "poison" (zahr) and "sweetness" (qand) represent things we instinctively label as bad or good. Rumi argues that these labels are not inherent to the things themselves but are determined by their effect on a specific individual in a specific context. What is poison for one (e.g., the watchman's pursuit for an ordinary citizen) can be an antidote (taryāq, M4:64) for another (the lover).

The second line powerfully illustrates this relativity. The same event or substance can be a "foot" (pā), enabling movement and progress for one person, while being a "fetter" (band), a chain that binds and restricts another. This principle, Rumi suggests, applies universally, dissolving the simplistic binary of absolute good and absolute evil into a more complex, relational understanding of reality.