In Ancient Greek philosophy, Plato implicitly employed the concept of differentia when he conceived his method of diairesis.
A theory was only provided by Porphyry's explicit treatment of the predicables presented in his Isagoge.
The elaborate scholastic theory of the predicables evolved οn the basis of Boethius' translation of the Isagoge, where the Greek term diaphora was rendered in Latin as "differentia".
Although the primary meaning of "differentia" is logical or second-order, it may under certain assumptions have an ontological, first-order application.
[1] If, on the other hand, any mind-independent structuring on the part of the essence is denied (like in Thomism or Suárezianism), then the partitioning of the essence into a generic and a differentiating part must be considered as merely "conceptua", whereas the actual realities corresponding to the differentia and to the genus evade as really the same.