 Though this method of obtaining a Curry sentence is based on a semantic feature of expressions, it still relies on property abstraction. Nonetheless, it can be viewed as a precursor to a wholly semantic version. (Rather than consider the above-introduced property, one could consider the predicate “applies to itself only if time is infinite”.) Accordingly, as Geach (1955) and Löb (1955) were the first to show, Curry sentences can be obtained using semantic principles alone, without any reliance on property abstraction. Their route corresponds to the informal argument, in  section 1.1,  involving the self-referential sentence \(k\) that reads “If \(k\) is true then time is infinite.”