In discussing the atomists' theory of vision modern accounts have quite neglected to take into account two sections of Alexander of Aphrodisias on this topic. Nearly identical in length and content, they contain objections to the atomist theory of vision by means of the . In form they consist of a series of questions purporting to contain atomist doctrine. Each question is followed by objections to its subject-matter. Most of the questions contain doctrine known to us already from other sources.