 Universals are conceptual entities: “These entities are such as can be named by parts of speech which are not substantives; they are such entities as qualities or relations” (1912 [1974: 90]). Because universals and particulars alike are possible objects of acquaintance both have to be real. However, according to Russell they are real in a different sense. Particulars have existence in time whereas universals have timeless being. The first ones exist, the other subsist. They form two different worlds in that the world of particulars consists of items that are “fleeting, vague, without sharp boundaries” whereas the world of universals “is unchangeable, rigid, exact” (1912 [1974: 100]).