وَالْأَجْسَامُ مُمَاثِلَةٌ يَصِحُّ عَلَى كُلِّ مَا يَصِحُّ عَلَى الْآخَرِ
Bodies are alike, so a kind of possibility applying to one may apply to another.
In the classical disputation, this premise resists the philosophers' claim that heavenly and terrestrial bodies are separated by a fundamental metaphysical barrier. It does not mean all bodies have identical observable qualities; it contests the denial of a particular rational possibility.
The premise belongs to its historical conceptual setting. It should not be presented as a modern experimental law concerning every form of physical matter.