Light-bearing

The high worth of diamonds comes from the same source: a super-hard, eternal substance, at the same time a light-bearing, translucent substance, a kind of solid emptiness, a marvelous optical illusion.

Others within the Cartesian tradition took the idea of a light-bearing medium in quite different directions. For instance, in 1690 Christiaan Huygens considered light to be a sequence of pulses traveling at a finite velocity within the medium.