 In other words, even in Göttingen in the 1920s a full understanding of the significance of the ideas Hilbert had introduced in 1917 was missing. The Hilbert school throughout the 1920s regarded first-order logic as a fragment of type theory, and made no argument for it as a uniquely favored system. It was not until the monograph Hilbert &amp; Ackermann 1928 (and the contemporaneous “Bologna Lecture”, Hilbert 1928) that Hilbert explicitly called attention to the completeness of first-order logic as an open question. That set the stage for the work of Gödel: but before coming to that, we need to take a chronological step backwards. 