A grace note (Wikipedia link) is a generally short-lived musical note, which serves to 'decorate' a melody, while not adding any time to it, or affecting the melody's structure in any significant way.
But why 'grace'? Who coined the term? Was it borrowed from another language, say, Italian? What was the logic behind associating the notion of 'grace' with this kind of musical note? Concerning the origin of 'grace note' in English, Etymonline says only this:
In music, "an embellishment not essential to the melody or harmony," 1650s.
To be specific, I am researching a particular kind of musical ornament that recurs in Medieval Latin treatises on music theory (Gregorian chant), the so-called vinnola vox. The descriptions reveal it as either a quick short passing note in a rising musical passage, or a brief neighboring note between two notes of the same pitch, like an acciaccatura or mordent. All of these musical ornaments are conceptually similar to a grace note.
Well, the Latin term vinnola or vinnula, describing a voice, means 'lovely', 'sweet', 'delightful', believed to be derived from the name Venus (goddess of love), about which Wikipedia says the following:
It [Venus] has connections to venerari ("to honour, to try to please") and venia ("grace, favour") through a possible common root in an Indo-European *wenes- or *u̯enis ("friend"). Their common Proto-Indo-European root is assumed as *wen- or *u̯en- "to strive for, wish for, desire, love").
Granted, there are about eight centuries between the 1650s and the time period of these manuscripts. Yet the coincidence is tempting to study.
So ... what do we know about the connotation of 'grace' in a grace note, and how far back does our knowledge reach?