 A sentence can be switched between true and false by adding a negative particle, for example, “It is not the case that” (laysa). But it matters where the negative particle is put; al-Fārābī discusses a number of cases, ad hoc with no clear overall pattern. One case that he discusses in detail is where the negation is attached to a noun, as when we form the noun “not-just” from the noun “just”. (Adjectives are counted as nouns.) Following Theophrastus (Fortenbaugh et al. 1992: 148–153) he identifies this kind of negation as “metathetic” (‘udūlī); he takes the resulting metathetic sentence to be an affirmation, not a denial. Nothing can be both just and not-just, but there are things that are neither, for example infants. So an infant is not just, but it is also not not-just. For a similar reason the infant is not unjust. Also it is false that the infant is just, and false that it is not-just. Likewise it is false (rather than meaningless) that every heat is curvilinear ([Categories] 125.8). (Thom 2008 steers a clear path through these notions.)