 Al-Fārābī introduces a distinction between concepts that apply to a thing permanently and those (called accident, ‘araḍ) that apply only temporarily. As a result, concepts have a temporal regime, and language should reflect this. Al-Fārābī is at his most a priori here, claiming that the temporal regime of concepts should be represented by a system of three tenses: past, present, and future. We don’t know whether he simply failed to notice other ways in which time is represented in Arabic grammar (for example, continuous tenses and pluperfect constructions), or for some reason he dismissed these features as marginal. 