  We present a detailed analysis of Penrose's gravito-optical analogy between
the focusing effects of particular families of Ricci- and Weyl-curved spacetime
regions on the one hand, and anastigmatic and astigmatic optical lenses on the
other. We put the analogy in its historical context, investigate its underlying
assumptions, its range of validity, its proof of concept, and its application
in Penrose's study of the notion of energy flux in general relativity. Finally,
we examine the analogy within the framework of Norton's material theory of
induction.
