Alicia Garza has been campaigning since she was 12 years old. It’s no surprise then, that when she posted a “love letter to Black people" on Facebook in 2013, it sparked one of the biggest racial justice movements in history - Black Lives Matter.   Now the principal of the Black Futures Lab, Alicia has just released her debut book, 'The Purpose of Power'.   She speaks to Krishnan about writing the rules, the power of a ballot box and making Black people the heroes of their own stories.