Original: This was essentially the defining criterion of "sentimental" discovered in a dozen basic handbooks by Brian Wilkie (Wilkie, "What Is Sentimentality?"
Simplified: Before that it had simply menat "feeling", but it began be criticized for its "excessiveness" (too much), Wilkie 1967, took the example of Henry Clay Works maudlin lyric of Temperance propaganda, "Come Home, Father".