Post by CDB"By heart" in these expressions is surely transferred from an
originally more-restricted use with "learn" or "memorise". I have
heard that "par coeur" was originally "par choeur", i.e. "through
group repetition". Don't know if that's folk etymology, though. I
don't find much by way of confirmation in Google. There are about 60
French websites with the phrase "apprendre par choeur", but I find no
strong indication that that is the original form.
The ARTFL historic French dictionaries site is a good place to go to
investigate this sort of thing.
Nicot, Thresor de la langue française (1606)
Par cueur, Memoriter, Ex memoria exponere.
Apprendre par cueur, Prosequi memoria, Aliquid
memoriae mandare, Ediscere.
Dire par cueur, Recitare, Pronuntiare, Reddere
aliquid sine scripto.
Tout par cueur, Memoriter memorare.
And by the next dictionary, the spelling was today's "coeur." After a
great many figures of speech involving "heart":
Dictionnaire de L'Académie française, 1st Edition (1694)
Coeur signifie aussi, Memoire & souvenir. Il gardoit
cela dans son coeur. j'ay gravé cela dans mon coeur.
j'ay cela bien avant dans le coeur. apprendre une
chose par coeur. sçavoir des vers, une oraison, &c.
par coeur. reciter par coeur.
So memorizing, learning something "by heart," knowing it, reciting it by
heart, was good French then.
"Choeur" does show up in the 1694 dictionary, definited as a troupe of
musicians or a group of people who sing during a play -- a chorus or
choir. None of the early dictionaries suggest that it is used to mean a
method of recitation or learning. The 1832 dictionary says "en choeur"
means singing together or repeating in chorus. That's a bit of overlap
that might have given rise to your observation? Students chanted bits in
chorus in order to learn them by heart.
(In Dutch, the expression is to learn the thing "out one's head.")
--
Best -- Donna Richoux