‘Interlude: Galactic mediocrity’ outlines why the lack of unusual features in the Milky Way is important. The Scientific Revolution can be said to have begun when Copernicus postulated his heliocentric model. This ultimately led to the notion of terrestrial mediocrity: that there is nothing special about our place in the Universe. Hubble thought that the Milky Way was unusually large, but others, such as Arthur Eddington. Accurate measurement was needed, and this was not possible until the Hubble Space Telescope provided data on cosmological scale, and proved the mediocrity of the Milky Way.