We must consider next the work of distinction in itself.
First, the work of the first day; secondly, the work of the second day; thirdly the work of the third day.
Under the first head there are four points of inquiry:
A1 Whether the word light is used in its proper sense in speaking of spiritual things?
A2 Whether light, in corporeal things, is itself corporeal?
A3 Whether light is a quality?
A4 Whether light was fittingly made on the first day?