"Fourteen years before Kirsten Gillibrand succeeded Hillary Rodham Clinton as senator from New York, she heard her future mentor say these life-changing words: 'Decisions are being made every day in Washington, and if you are not part of those decisions, you might not like what they decide, and you'll have no one to blame but yourself.' A young corporate lawyer at the time, Gillibrand felt as if she'd been struck by lightning. She instantly knew that...