How do ruling passions lead characters into trouble in Ben Jonson's comedies?

In Ben Jonson’s comedies, characters are often driven by a "ruling passion" or "humour"—a dominant psychological idiosyncrasy or peculiar quality that consumes their personality. Jonson utilized the medieval and Renaissance medical theory of humours, which posited that an imbalance of bodily fluids could dictate a person's disposition. By metaphor, he applied this to his characters, showing how a single obsession or mannerism could possess them, body and soul.12

These ruling passions lead characters into trouble by making them predictable, unbalanced, and prone to folly. Because these characters are governed by a singular, intense focus—such as greed in Volpone or gullibility in The Alchemist—they become easy targets for manipulation. In Volpone, for example, the greed of the fortune hunters blinds them to the reality of their situation, leading them to sacrifice their own interests and dignity in pursuit of a false inheritance. Ultimately, Jonson uses these caricatures to expose human vices, as the characters' inability to moderate their ruling passions inevitably results in their downfall or punishment.1234