T
The_Prodigal
Guest
I agree that “in albis” becoming “eostrum” is basically impossible. The two words don’t even share any consonants, aside from, but that’s just a declension in the Latin. So actually, the words changed a lot less than he must suppose. I’m not sure what you mean by bringing Grimm’s Law into this, other than as a clever name-drop, since that sound change occurred long before Christ, and so any Christian-related borrowings from Latin to Germanic would not be phonologized anyways.
Mr. McRoy’s claim in the link provided by Ginger2 is that “eostarum” was a calque, not a direct borrowing from Latin.
According to the theory (erroneous IMO), the Germans chose a word in their own language that translated in albis. There is no assertion that the phrase in albis became eostarum by phonetic change. As McRoy rather vaguely puts it, the phrase “found its way into Old High German as eostarum.”
Incidentally, not only does in albis not mean “dawn,” but in the Grimms’ dictionary, the idea that eostar(um) meant “dawn” is pure speculation, and based on its supposed connection with the word for “east”! AFAIK, eostar or a similar form is not attested in any language with the meaning “dawn.”