“These are indeed dark times,” Aaron Sachs, author of Up from the Depths: Herman Melville, Lewis Mumford, and Rediscovery in Dark Times, says at the start of this episode of The World in Time. “And as a historian, I’ve been wondering my whole professional life how these dark times compare to other dark times…I feel like it’s my job as a historian to to really investigate the claim that there’s no precedent for what we’re going through, because that idea is really disheartening in a lot of ways.” This week on the podcast, Lewis H. Lapham speaks with Aaron Sachs, author of “Up from the Depths: Herman Melville, Lewis Mumford, and Rediscovery in Dark Times,” about dark times and white whales.