What's this -れり ending?


I'm really a 初心者 when it comes to Classical Japanese, and I guess that is what
I have here...

> 一日の苦労は一日にて足れり. 【聖】  
>  _Sufficient unto the day is the evil thereof._

Please, can someone tell me what this is about? 足れり comes from 足りる or is it
from 足る?  
Moreover, I don't get it... Even with the translation, because I'm not an
English native speaker either. So can you put the japanese sentence and/or the
English translation in a simpler way, please?




足れり is basically the Old/Middle Japanese version of what in Modern Japanese
would be 足りている. It consists of 足り (the ren'youkei of 足る) plus あり (modern ある).
(It's not 足りあり because of Old Japanese's vowel cluster mergers: /ia/ > /e/.)
Modern Japanese 足りている has exactly the same structure as the Middle Japanese
version, just with a different conjunction form (-て instead of the bare
ren'youkei) and a different 'to be' verb (いる instead of ある); and in this case,
the verb has jumped classes since Middle Japanese and is now the kami-ichidan
足りる instead of the yodan 足る. (足る is apparently valid in Modern Japanese, but I
at least have never seen it used outside of fossilised constructions or
deliberately archaic speech - the vast majority of the time Modern Japanese
uses 足りる.)

The sentence as a whole could be somewhat loosely translated as 'the hardships
of one day are enough for that day'. A literal translation of 一日にて足れり here
sounds weird in English, but it basically means something like 'the action of
being enough is complete within [that] one day'.




足れり is basically the Old/Middle Japanese version of what in Modern Japanese
would be 足りている. It consists of 足り (the ren'youkei of 足る) plus あり (modern ある).
(It's not 足りあり because of Old Japanese's vowel cluster mergers: /ia/ > /e/.)
Modern Japanese 足りている has exactly the same structure as the Middle Japanese
version, just with a different conjunction form (-て instead of the bare
ren'youkei) and a different 'to be' verb (いる instead of ある); and in this case,
the verb has jumped classes since Middle Japanese and is now the kami-ichidan
足りる instead of the yodan 足る. (足る is apparently valid in Modern Japanese, but I
at least have never seen it used outside of fossilised constructions or
deliberately archaic speech - the vast majority of the time Modern Japanese
uses 足りる.)

The sentence as a whole could be somewhat loosely translated as 'the hardships
of one day are enough for that day'. A literal translation of 一日にて足れり here
sounds weird in English, but it basically means something like 'the action of
being enough is complete within [that] one day'.

