لو لم تكن نية الجوزاء خدمته لما رأيت عليها عقد منتطق
Had Gemini not intended to serve him, you would not have seen it wearing a belt.
The poet connects the visible configuration of the constellation to a conscious intention to serve. Observing a pattern of stars is one thing; claiming that they deliberately dress for service is another, literally impossible relation.
The impossible supposition serves an expressive purpose: it magnifies the patron until even the heavens seem to attend upon him.