Hilbert's Proof of His Irreducibility Theorem
  Hilbert's Irreducibility Theorem is a cornerstone that joins areas of analysis and number theory. Both the genesis and genius of its proof involved combining real analysis and combinatorics. We try to expose the motivations that led Hilbert to this synthesis. Hilbert's famous Cube Lemma supplied fuel for the proof but without the analytical foundation and framework it would have been heating empty air. The lemma is said to presage Ramsey Theory but we note differences in motivation. 
Mark B. Villarino, Bill Gasarch, Kenneth Regan
math.HO