- Josh Brolin - Narrator: Locked in strata deep under ground, coal. Ancient rain forests, compacted into peat, and compressed. Buried for 300 million years. The sun's energy trapped in every piece.
- Mark Frauenfelder: Coal is this magical stuff. It just looks like a black hunk of greasy dirt. But there's so much energy embedded in that, that it's really, it's as precious as a jewel.
- Dan McNichol: [about miners] It would be said of immigrants, you'd rarely see one with gray hair. A worker was lucky to live long enough to have gray hair.
- Josh Brolin - Narrator: [about new railroad line] People can travel further in hours than the previous generation did in a lifetime.
- Dan McNichol: [about cholera epidemic] The entire city of London, the most advanced metropolitan area in the world, was really an open sewer.
- Prof. H.W. Brands: [about the American Civil War] If you think of it as a marriage, the marriage had fallen apart. The differences had become irreconcilable.