I missed something, where does "light" come from? How did we get from "jour d'aujourd'hui" to "connaisance d'aujourd'hui" - where's the intermediate "lumière d'aujourd'hui"?
"Jour" is polysemic, it literally means "day", but metaphorically it also means "light". For instance, "voir quelque chose sous un nouveau jour" means "to see something under a new light", rather than "a new day".