Language defines us as a species, placing humans head and shoulders above even the most proficient animal communicators. But it also beguiles us with its endless mysteries, allowing us to ponder why different languages emerged, why there isn't simply a single language, how languages change over time and whether that's good or bad, and how languages die out and become extinct.

Between 1861 and 1865, the clash of the greatest armies the Western hemisphere had ever seen turned small towns, little-known streams, and obscure meadows in the American countryside into names we will always remember. In those great battles, those streams ran red with blood-and the United States was truly born.

Eating is an indispensable human activity. As a result, whether we realize it or not, the drive to obtain food has been a major catalyst across all of history, from prehistoric times to the present. Epicure Jean-Anthelme Brillat-Savarin said it best: "Gastronomy governs the whole life of man."

Economic forces are everywhere around you. But that doesn't mean you need to passively accept whatever outcome those forces might press upon you. Instead, with these 12 fast-moving and crystal clear lectures, you can learn how to use a small handful of basic nuts-and-bolts principles to turn those same forces to your own advantage.

Jazz is a uniquely American art form, one of America's great contributions to not only musical culture, but world culture, with each generation of musicians applying new levels of creativity that take the music in unexpected directions that defy definition, category, and stagnation.

Now you can learn the basics and history of this intoxicating genre in an eight-lecture series that is as free-flowing and original as the art form itself.

"It doesn't take an Einstein to understand modern physics," says Professor Wolfson at the outset of these 24 lectures on what may be the most important subjects in the universe: relativity and quantum physics. Both have reputations for complexity. But the basic ideas behind them are, in fact, simple and comprehensible by anyone. These dynamic and illuminating lectures begin with a brief overview of theories of physical reality starting with Aristotle and culminating in Newtonian or "classical" physics. After that, you'll follow along as Professor Wolfson outlines the logic that led to Einstein's profound theory of special relativity and the simple yet far-reaching insight on which it rests. With that insight in mind, you'll move on to consider Einstein's theory of general relativity and its interpretation of gravitation in terms of the curvature of space and time.From there, you'll embark on a dazzling exploration of how inquiry into matter at the atomic and subatomic scales led to quandaries that are resolved-or at least clarified-by quantum mechanics, a vision of physical reality so profound and so at odds with our experience that it nearly defies language.By bringing relativity and quantum mechanics into the same picture, you'll chart the development of fascinating hypotheses about the origin, development, and possible futures of the entire universe, as well as the possibility that physics can produce a "theory of everything" to account for all aspects of the physical world. But the goal throughout these lectures remains the same: to present the key ideas of modern physics in a way that makes them clear to the interested layperson.

No skill is more important in today's world than being able to think about, understand, and act on information in an effective and responsible way. What's more, at no point in human history have we had access to so much information, with such relative ease, as we do in the 21st century. But because misinformation out there has increased as well, critical thinking is more important than ever. These 24 rewarding lectures equip you with the knowledge and techniques you need to become a savvier, sharper critical thinker in your professional and personal life.

With this exciting and historically rich six-lecture course, experience for yourself the drama of this dynamic year in medieval history, centered on the landmark Norman Conquest. Taking you from the shores of Scandinavia and France to the battlefields of the English countryside, these lectures will plunge you into a world of fierce Viking warriors, powerful noble families, politically charged marriages, tense succession crises, epic military invasions, and much more.Your journey starts in the 10th and early 11th centuries, when power in England and Normandy was very much up for grabs-and when the small island nation was under continuous assault from Viking forces. Professor Paxton helps you gain a solid grasp of the complex political alliances and shifting relationships between figures such as Emma of Normandy, Cnut, and Edward the Confessor. She also recounts for you the two seminal battles that pitted England against the Scandinavians and the Normans: the Battle of Stamford Bridge and the Battle of Hastings. Throughout the lectures, Dr. Paxton opens your eyes to continued debates and controversies over this year and offers her own take on the Norman Conquest's enduring legacy and the fascinating results of this epic clash. By exploring the year 1066-what led up to it, what happened during that fateful year, and what changed as a result-you'll gain a sharper perspective and a greater understanding of everything that would come afterward.

The Greek myths are amongst the greatest stories ever told, passed down through millennia and inspiring writers and artists as varied as Shakespeare, Michelangelo, James Joyce and Walt Disney. They are embedded deeply in the traditions, tales and cultural DNA of the West. You'll fall in love with Zeus, marvel at the birth of Athena, wince at Cronus and Gaia's revenge on Ouranos, weep with King Midas and hunt with the beautiful and ferocious Artemis.

Following the surge of interest and pride in Celtic identity since the 19th century, much of what we thought we knew about the Celts has been radically transformed. In The Celtic World, discover the incredible story of the Celtic-speaking peoples, whose art, language, and culture once spread from Ireland to Austria. This series of 24 enlightening lectures explains the traditional historical view of who the Celts were, then contrasts it with brand-new evidence from DNA analysis and archeology that totally changes our perspective on where the Celts came from.

Military history often highlights successes and suggests a sense of inevitability about victory, but there is so much that can be gleaned from considering failures. Study these crucibles of history to gain a better understanding of why a civilization took - or didn't take - a particular path.

Take a riveting tour of the Italian peninsula, from the glittering canals of Venice to the lavish papal apartments and ancient ruins of Rome. In these 24 lectures, Professor Bartlett traces the development of the Italian city-states of the Middle Ages and the Renaissance, showing how the modern nation of Italy was forged out of the rivalries, allegiances, and traditions of a vibrant and diverse people.

The sun is setting on the Western world. Slowly but surely, the direction in which the world spins has reversed: where for the last five centuries the globe turned westward on its axis, it now turns to the east.... For centuries, fame and fortune were to be found in the West - in the New World of the Americas. Today it is the East that calls out to those in search of adventure and riches. The region stretching from Eastern Europe and sweeping right across Central Asia, deep into China and India, is taking center stage.

Every day of your life is spent surrounded by mysteries that involve what appear to be rather ordinary human behaviors. What makes you happy? Where did your personality come from? Why do you have trouble controlling certain behaviors? Why do you behave differently as an adult than you did as an adolescent?Since the start of recorded history, and probably even before, people have been interested in answering questions about why we behave the way we do.