Parul Sehgal: An ode to envy

What is jealousy? What drives it, and why do we secretly love it? No study has ever been able to capture its "loneliness, longevity, grim thrill" -- that is, says Parul Sehgal, except for fiction. In an eloquent meditation she scours pages from literature to show how jealousy is not so different from a quest for knowledge.