  I review two fundamental contributions that Fred Hoyle made to the theory of
galaxy formation. Hoyle was the first to propose that protogalaxies acquired
their angular momentum via tidal torques from neighbouring perturbations during
a period of gravitational instability. To my knowledge, he was also the first
to suggest that the masses of galaxies could be explained by the requirement
that primordial gas clouds cool radiatively on a suitable timescale. Tidal
torques and cooling arguments play a central role in the modern theory of
galaxy formation. It is a measure of Hoyle's breadth and inventiveness that he
recognised the importance of these processes at such an early stage in the
history of the subject.
