Where does “mōntag” come from?

mōntag (Middle High German) comes from Old High German mānotag, from Proto-Germanic *mānini dag, from Latin dies Lūnae, from Ancient Greek σελήνη, from Ancient Greek Σέλας — light, brightness, the bright flame or blaze of fire.

Ancestry of “mōntag”, step by step

Step	Language	Word	Meaning
1	Old High German	mānotag	Monday
2	Proto-Germanic	*mānini dag	—
3	Latin	dies Lūnae	Monday
4	Ancient Greek	σελήνη	moon; month; a moon-shaped cake
5	Ancient Greek	Σέλας	light, brightness, the bright flame or blaze of fire

Every word from Ancient Greek Σέλας →Every word from Ancient Greek σελήνη →Every word from Latin dies Lūnae →