Mathal (literally: similitude) is one of the best-known features in the Qur’an. It includes different phenomena in English ranging from “extended explicit comparisons […] [to] example stories, parables […] and allegories” (Zahniser 2004). Poets, too, had a habit of striking parables (amthāl) in their verse, a fact that did not go unnoticed by the medieval Arabic literary critics. The critics dealt with this topic under several headings, most notably tamthīl (literally, adducing a mathal), but also mumāthala, tadhyīl, and takhyīl. The critics’ illustrative examples always include Qur’anic verses. In this paper I explore to what extent the critics’ insights can reveal something about the structure of the mathal within the larger discourse and about the aim of inserting it, both in poetry and in the Qur’an. In doing so I ask the following two questions: (1) Is there a “prototype” mathal that the critics associate with the Qur’an, and if so, what was its nature? Preliminary research points to the extended explicit comparison but also to parables. I will take into account the Qur’an’s own statements about mathal. (2) Can the poetic examples that the critics adduce tell us something about the structure (or grammar) of mathal in the Qur’an, i.e., its placement within the larger Sura or subsection within the Sura? In poetry the mathal (or at least one type of mathal) must appear at the end of a line, after the poet has already established his so-called lesson or moral. The biggest challenge to this study is the varying meanings of mathal and tamthīl in the sources, even within those by terminologically minded scholars such as ʿAbd al-Qāhir al-Jurjānī (5th/11th c.).