I met David Razu Aznar, graduating from the Kennedy School today. David, stand up. He’s a former city councilor who successfully led the battle to make Mexico City the first Latin American city to pass marriage equality -- even before San Francisco.

This is my story too. A student in a dorm room, connecting one community at a time, and keeping at it until one day we connect the whole world.

Change starts local. Even global changes start small -- with people like us. In our generation, the struggle of whether we connect more, whether we achieve our biggest opportunities, comes down to this -- your ability to build communities and create a world where every single person has a sense of purpose.

Class of 2017, you are graduating into a world that needs purpose. It's up to you to create it.

Now, you may be thinking: can I really do this?

Remember when I told you about that class I taught at the Boys and Girls Club? One day after class I was talking to them about college, and one of my top students raised his hand and said he wasn't sure he could go because he's undocumented. He didn't know if they'd let him in.

Last year I took him out to breakfast for his birthday. I wanted to get him a present, so I asked him and he started talking about students he saw struggling and said "You know, I'd really just like a book on social justice."

I was blown away. Here's a young guy who has every reason to be cynical. He didn't know if the country he calls home -- the only one he's known -- would deny him his dream of going to college. But he wasn't feeling sorry for himself. He wasn't even thinking of himself. He has a greater sense of purpose, and he's going to bring people along with him.

It says something about our current situation that I can't even say his name because I don't want to put him at risk. But if a high school senior who doesn't know what the future holds can do his part to move the world forward, then we owe it to the world to do our part too.

Before you walk out those gates one last time, as we sit in front of Memorial Church, I am reminded of a prayer, Mi Shebeirach, that I say whenever I face a challenge, that I sing to my daughter thinking about her future when I tuck her into bed. It goes:

"May the source of strength, who blessed the ones before us, help us *find the courage* to make our lives a blessing."

I hope you find the courage to make your life a blessing.

Congratulations, Class of '17! Good luck out there.