 Here “Zayd” , “horse”, “animal”, “stone” signify simple primary concepts; the proper name “Zayd” signifies a particular (juz’), and the other three words signify universals (kullī). “Every” and “some” are quantifiers (sūr), and “is” is a copula (rābiṭ) signifying the connection between two primary concepts so as to form an affirmation or a denial ([Commentary on De Interpretatione] 102.17) Al-Fārābī groups all these words into two classes: noun (ism) for those signifying primary concepts, and particle (ḥarf) for the remainder. (Adjectives count as nouns.) He makes clear that the particles are a disparate group and need further classification ([Expressions] 42.8–12). 