Although stating explicitly the difference between de re and de dictomodalities, Ibn-Sina deals only with de re modality and its divisions, neglecting de dicto modality and its importance in Islamic philosophy. Among the uses of de dicto modality, one is predicating species on genus: in Ibn-Sina’s view, the proposition "animal is (a) human" is necessary or impossible if human individuals are considered, but possible if human’s essence is considered. A proposition involving "the possibility of predicating species on genus" (such as "animal is possibly human") lacks any name in ancient logic, so I name it "essential proposition". It is not contained in the classical divisions in ancient logic because it is not any one of the singular, natural, indefinite, or quantified propositions, nor is it haml e awwali or haml e shaie. The secret of its being out of the classical divisions is that they are only for abstract propositions and de re modalities, whereas it is not in principle a de re modality and has to be regarded as de dicto one.