"par coeur" origin

The Engloish expression "by heart" or "off by heart" comes from the
French "par coeur" but can anbyone tell me the process in which thr
French term came to mean to know something from memory. I' ve heard
speculation that "par coeur" was originally "par choeur", i.e. "through

group repetition," but I wonder if this is merely folk etymology.

.