  Weyl’s claim is that because general relativity is an inherently  local field theory, its validity and soundness is  essentially independent of global cosmological considerations.  However, if we wish to introduce such global considerations into our  local physics, then we can do so only on the basis of additional  assumptions, such as, for example, the Cosmological Principle,  already mentioned. In 1923 Weyl (1923b, §39) introduced another  cosmological assumption, namely, the so-called Weyl  Postulate. De Sitter’s solution and the new astronomical  discoveries in the early 1920’s, which suggested that the universe is not static but expanding, led to a drastic change in thinking about  the nature of the universe and an increased scepticism towards  Einstein’s model of a static universe. In 1923, Weyl (1923b,  §39) notes in the fifth edition of Raum Zeit Materie,  that despite its attractiveness, Einstein’s cosmology suffers from  serious defects. Weyl begins by pointing out that spectroscopic  results indicate that the stars have an age. Weyl continued, 