  I give an epistemological analysis of the developments of relativistic
cosmology from 1917 to 1966, based on the seminal articles by Einstein, de
Sitter, Friedmann, Lemaitre, Hubble, Gamow and other historical figures of the
field. It appears that most of the ingredients of the present-day standard
cosmological model, including the acceleration of the expansion due to a
repulsive dark energy, the interpretation of the cosmological constant as
vacuum energy or the possible non-trivial topology of space, had been
anticipated by Georges Lemaitre, although his articles remain mostly unquoted.
