 The square could be taken to refer to modals de dicto or singular modals de re (see below.) Abelard tried to define the opposed relations between quantified de re modals as well, mistakenly thinking that these were the same as those between singular modal propositions (Glossae super Perihermeneias XII, 468–471, 530–544). This question was not much discussed before its satisfactory solution in fourteenth-century modal semantics. (See Hughes 1989 and his description of Buridan’s octagon of modal opposites and equipollences.) While possibile and contingens are treated as synonyms in the figure, it became more usual to associate the former with one-sided possibility (not impossible) and the latter with two-sided possibility (neither necessary nor impossible).  