“Does history have an arrow? That’s a profound question. Because if you think history has an arrow, it changes how you feel about the future.” —Chris Anderson, introducing Robert Wright. [Session write up | Photo]

“We are witnessing a collision between our civilization and the earth … We have no more than 10 years within which we can make a difference; otherwise it’s too late. It’s a question of political will, but in a democracy political will is a renewable resource.” —Al Gore, sounding the alarm on climate change [Session write up | Photos | Past post: CelebrityWatch: Al Gore]

“I used to be a lightbulb. Now I’m a laser.” —Nicholas Negroponte, explaining his decision to step down as chairman of the MIT Media Lab and focus on implementing his One Laptop Per Child program. [Session write up | Photo | Past post: $100 (lime green) laptop unveiled]

“You can move much faster if you’re healthy first than if you’re wealthy first.” —Hans Rosling, narrating a time-lapse graph, illustrating the fate of nations’ development over the last 40 years. [Session write up | Photo | Past posts: Hans Rosling, the great visualizer, to speak at TED and Visualizing Global Trends]

“Google could really use one of these in their lobby.” —Jeff Han, demonstrating his intuitive “interface-free” multi-sensing computer screen [Session write-up | Background on Jeff Han | Photo]