We have mentioned several times in this biography that Minkowski and Hilbert were close friends. Less well known is the fact that Minkowski actually suggested to Hilbert what he should take as the theme for his famous 1900 lecture in Paris. Minkowski, in a letter to Hilbert written on 5 January 1900, writes:
What would have the greatest impact would be an attempt to give a preview of the future, i.e. a sketch of the problems with which future mathematicians should occupy themselves. In this way you could perhaps make sure that people would talk about your lecture for decades in the future.