  Before the establishment of the hot Big Bang scenario as the modern paradigm
of cosmology, it faced several early competitors : the so-called stationary
cosmological models. There were truly plural and independent approaches
incorporating cosmic expansion but without time evolution of the total
cosmological density, thanks to the inclusion of some processes of continuous
matter creation. We distinguish here three different independent motivations
leading to a stationary vision of the universe. First, Einstein's concerns on
the asymptotic behaviour of gravitation led him to consider continuous matter
creation in a recently discovered unpublished work dated of 1931. Second, there
is the quest by Dirac and Jordan for a scientific explanation of numerical
coincidences in the values of fundamental constants, leading both to a time
variation of Newton's constant and spontaneous matter creation. The third one
appears in the steady-state theory of Bondi and Gold as the postulate of the
Perfect Cosmological Principle according to which the properties of the
universe do not depend in any way of the location and the epoch of the
observer. Hoyle developed a mathematical model of spontaneous matter creation
from a modification of general relativity that should be considered as a direct
legacy of Einstein's and Dirac's approaches. Hoyle's model allows obtaining a
"\textit{wide cosmological principle}" as an end-product, echoing Bondi and
Gold's Perfect Cosmological Principle. Somewhat ironically, many modern key
questions in hot Big Bang cosmology, like dark energy and inflation, can
therefore be directly related to the physical motivations of the early
stationary cosmologies.
