 The 1950s saw a deepening of Gödel’s involvement with philosophy: In 1951 Gödel delivered a philosophical lecture at Brown University, usually referred to as the Gibbs Lecture, entitled “Some Basic Theorems on the Foundations of Mathematics and Their Philosophical Implications” (Gödel *1951). From 1953 to 1959 Gödel worked on a submission to the Schilpp volume on Rudolf Carnap entitled “Is Mathematics a Syntax of Language?” (Gödel *1953/9-III, Gödel *1953/9-V). Gödel published neither of these two important manuscripts in his lifetime, although both would appear on two lists which were found in the Gödel Nachlass, entitled “Was ich publizieren könnte.” (In English: “What I could publish.” Both manuscripts eventually appeared in Gödel 1995.) By the decade’s close Gödel developed a serious interest in  phenomenology.[5]