 Every attribute of a real object is itself something real. An adherence is an attribute of something real, i.e., of a substance or of another adherence. The adherences of a human being or of a mind must therefore themselves belong to World 2 or World 1. They are therefore particulars and not universals. This view is supported by Bolzano’s claim that each “private” mental phenomenon, such as a feeling, a desire, a volition or a thought (i.e., a subjective idea or a subjective proposition), is an attribute of the individual mind that “has” it, where ‘has’ expresses the copula (WL II, 69). It is a particular attribute of an individual (or, in today’s terminology, a trope) that cannot be shared by any other individual: if both, \([A_1\) has \(b]\) and \([A_2\) has \(b]\), are true and \(b\) is a subjective idea or any other mental phenomenon, then \(A_1\) must be identical with \(A_2\). Bolzano’s theory of propositions, however, conveys the impression that attributes are universals. For in the standard examples he gives for a true proposition \([A\) has \(b]\), the attribute \(b\) is a universal, such as erudition, that can be shared by different objects (WL I, 130). Obviously, we must admit that some of Bolzano’s attributes are universals and others are particulars. In this case, however, the word ‘has’, which expresses the copula of each proposition according to Bolzano, is used ambiguously by him.