If they were to retain this even under a change of velocity which makes it impossible for anything like hardness to be, then hardness does not belong to the being of these ratione ostendi potest, et pondus, et colorem, et alias omnes eiusmodi qualitates, quae in materia corporea sentiuntur, ex ea tolli posse, ipsa integra remanente: unde sequitur, a nulla ex illis eius (sc.