first up, a conversation with harvard sociologist sara lawrence-lightfoot. she was the first african- american woman to have a professorship at harvard named in her honor. she has a new book called "exit". also, luciana souza is here. we are glad you have joined us. coming up, right now. >> there is a saying that dr. king had that said there is always the right time to do the right thing. i try to live my life every day by doing the right thing. we know that we are only halfway to completely eliminating hunger and we have work to do. walmart committed $2 billion to fighting hunger in the u.s. as we work together, we can stamp hunger out. >> and by contributions to your pbs station from viewers like you. thank you. tavis: sara lawrence-lightfoot is a renowned harvard professor and author. her latest bdisalle cdle "exit: the endings that set us free." good to have the on this program. >> it is great to be here. thank you, tavis. tavis: tell me more about your fascination with endings. >> i have noticed for a very long time, from when i was very young, how we d