Les agréments

“…an abundance of everything that is able to enrich, sweeten and enliven in every way whatever might otherwise be too simple, crude or dull in the melody or harmony of the music.”
—Georg Muffat, Florilegium secundum (1698)

“The embellishments or graces…serve, in accordance with the temper of the piece, to excite cheer and gaiety, while the simple appoggiaturas, on the contrary, arouse tenderness and melancholy. …the little embellishments should be used like seasoning at a meal; if the prevailing sentiment is taken as the guiding principle, propriety will be maintained, and one passion will never be transformed into another.”
—Johann Joachim Quantz, On playing the Flute (1752)

“Arbitrary agréments often diminish the beauty of a melody; the essential agréments add to it. A well-composed piece can dispense with capricious ornaments, but it cannot get along without those agréments that are essential to the goût du chant.”
—Friedrich Wilhelm Marpurg, Principes de clavecin (1756)

“Most 17th French musical publications carefully codified (via engraved tables) the precise ornaments desired in their music. By doing so, they created a specific international language for Baroque ornamentation. An intimate understanding of these agréments is absolutely necessary to performances of Bach, Handel and yes, also Mozart.”
—Dr. Julianne Baird