The promise of America is that the country is based on an idea, one where everyone is created equal and equally free to chart their own course. From 13 newly independent states ratifying a national constitution to the heated debates in the halls of Congress today, American politics is about negotiation over what our country is—and where we are going.

Railways are one of the most important inventions in modern history. From the 1825 opening of the Stockton and Darlington Railway in England, trains revolutionized both travel and trade and radically changed the way we experience the world. In the 24 richly illustrated lectures of How Railways Transformed the World, you’ll experience the amazing world and impact of railways, from the early 19th century to today’s futuristic trains, including extensive material on the pleasure and appeal of rail travel today.

“Who are you?” Chances are you’d answer this question by describing the highlights of your personality and life experiences. But if you’d been asked this same question yesterday, you might have responded with a slightly different description. Does that mean you are a particular person today but were a different person yesterday? And what about tomorrow? Welcome to the slippery, shape-shifting nature of memory. As Professor Gabrielle Principe reveals, “you” are the conglomeration of the often-unreliable information your brain decides to feed you at any given moment.

Thought experiments are “what if” scenarios that invite us to look carefully at how we think and view the world. They’ve been used throughout history by philosophers and other thinkers to explore our intuitions and ways of reasoning, to find solutions to problems, and to expand our knowledge of ourselves and the world. In these 24 eye-opening lectures, Professor Breyer takes you deeply into the historical tradition of thought experiments, shining a light on both the purpose and the outcomes of these compelling mental voyages.

The issues addressed by macroeconomics are all around you, all the time—from taxes to inflation to mention of the GDP on the nightly news. By learning the principles of macroeconomics, you’ll be able to go beyond simply hearing the terms to better understanding their relationships to each other and how they create the economic environment in which you live. In fact, macroeconomics with its “big-picture glasses” allows you to better ask—and better try to answer—the biggest questions of our time, questions that impact the lives of billions of people.