 Skolem in the winter of 1915–16 visited Göttingen, where he discussed set theory with Felix Bernstein; there is no sign that he met Hilbert. He was already at this time familiar with Löwenheim’s theorem, and knew of its paradoxical implications for Zermelo’s axiomatization of set theory: specifically, that a first-order axiomatization of the theory of non-denumerable sets would have a denumerable model. He did not at the time publish on these topics because, as he later said: