 The conversion thus does not go through, since none of the terms in the two premises are common. Mullā Sạdrā then concludes his account of motion by repeating and defending Avicenna’s idea that the form of motion as it exists in the world involves motion at an instant, and it is this account that comes to predominate in the Muslim East (certainly Muslim India) until at least as late as the 1850s. (For a discussion of Avicenna’s conception of motion and the post-Avicennan reception of that definition see McGinnis (2018).)