You must read Justin's piece in its entirety, but as a preview here are some of my favorite quotations from it:
Technology, community, and capitalism combine to make Silicon Valley the potential epicenter of vast positive change.
And with increasingly severe threats to our survival — rapid climate change, an unstable international economy, and unsustainable energy consumption — it is more important than ever that we... change the world, foster happiness and alleviate suffering, for us and our fellow beings.
[I]n the face of threats to humanity’s future on the one hand and the extraordinary potential of mankind on the other, at some point we must ask: are we capable of more?
Life is short, youth is finite, and opportunities endless. Have you found the intersection of your passion and the potential for world-shaping positive impact?
Don’t lose the fire you started with. If you’re going to devote the best years of your life to your work, have enough love for yourself and the world around you to work on something that matters to you deeply... in order to do great things, we must attempt great things.