As contributed by Bro. Brad Newton:

One of the first metaphysical and scientific references to light in modern science and theology is by Robert Grosseteste, ON LIGHT or THE BEGINNING OF FORMS.

In latin with a nice diagram:

http://www.fh-augsburg.de/~harsch/Chronologia/Lspost13/Grosseteste/gro_luce.html

English translation is here:

http://www.colorado.edu/StudentGroups/lcm/lunch/deluce.html