» Tue Oct 12, 2010 12:32 pm
Perhaps Trevelyan was referring to the fact that Mundus, the anchor of Existence, harvests Magicka (light) FROM Aetherius. Welkynd stones, stones of/from Creation (Mundus/Aetherius) are the counterparts of Sigil stones, stones of/from Destruction (Oblivion).
http://www.imperial-library.info/obbooks/magic_sky.shtml states that light is one of the 4 elements that comprise the Mundus, possibly the most important.