Planet Money's Stacey Vanek Smith has reported on business and the economy for over 15 years now. She told NPR's Guy Raz that over that time, she's seen the same barriers blocking advancement for women in the workplace again and again. Recently, she's started to recognize that a lot of tools to move past those barriers can be found in the work of Italian philosopher Niccolò Machiavelli. Vanek Smith lays out these solutions in her new book, Machiavelli for Women: Defend Your Worth, Grow Your Ambition, and Win the Workplace.