"My duty is to my heart" . . .
Duty is a category which is by definition separate from "heart." It represents all those things -- family, tradition, state, law -- which have a claim on us that transcends personal affection and selfish desire. For goodness' sake, what does our generation make of Antigone? ("Antigone? Huh?" -- never mind.)
At the end of Edith Wharton's The Age of Innocence (and in the finale of Martin Scorcese's film adaptation), the story's protagonist, Newland Archer, watches from a bench as his grown son enters the home of the woman whose love Archer had renounced years before for the sake of his family. Is Archer a sad figure or a tragic figure? Is he simply a pathetic man who has "missed out" on the love of his life? Or is he a man who has sacrificed his great love -- a love which, however grand, is ultimately only personal -- to the demands of duty and who has lived to see his sacrifice become quaint in the eyes of the younger generation? I suppose he is, in a way, both men; he is a tragic figure poised on the brink of a brave new world which looks back at him and says, "How sad, dude -- don't you know your duty is to your heart?"