 A third influential alternative was proposed by Thomas Aquinas. Thomas argued that the substantial forms of the elements are destroyed and that only the qualities contribute to the mixture. Thomas shares Avicenna’s conviction that every form presupposes a certain material disposition, which is the mean quality characteristic of the compound. But he deviates from Avicenna in that the forms of the elements are not preserved; they are only virtually present in the compound, in that their powers survive (De mixtione elementorum, cf. Summa theol. Ia q. 76 a. 4). Thomas’ position found many adherents. Its problem is that physical bodies cannot truly be called mixtures of elements.