 Geach notes that the semantic paradox that results from a sentence like \(T\langle \xi \rangle\) resembles “the Curry paradox in set theory”. Löb, who doesn’t mention Curry’s work, credits the paradox to a referee’s observation about the proof of what is now known as Löb’s theorem concerning provability (see entry on  Gödel’s incompleteness theorems).  The referee, now known to have been Leon Henkin (Halbach &amp; Visser 2014: 257), suggested that the method Löb used in his proof “leads to a new derivation of paradoxes in natural language”, namely the informal argument of  section 1.1  above.[12] 