 It is important to note that “+” is a sign of affirmation and not a predicate. For example, Sundholm (2009: 274) argues that Brentano simply “rediscovered” an idea of Bolzano. According to Sundholm, Bolzano takes “A exists” to express the propositions that the idea [A] has an object; “A does not exist” expresses the negation of this property. The appearance that Brentano recycles this view is dispelled when we notice that “+” does not express a presentation, but only determines in which mode a content is to be thought.