In the 21st century, Carl Gustav Jung (1875-1961) remains one of the key figures in the field of analytical psychology - and Psychological Types, or The Psychology of Individuation, published in 1921, is one of his most influential works. It was written during the decade after the publication of Psychology of the Unconscious (1912), which effectively ended his friendship and collaboration with Sigmund Freud.

What are the most common dreams and why do we have them? What does a dream about death mean? What do dreams of swimming, failing, or flying symbolize? First published by Sigmund Freud in 1899, The Interpretation of Dreams considers why we dream and what it means in the larger picture of our psychological lives.

In On the Genealogy of Morals, subtitled "A Polemic", Nietzsche furthers his pursuit of a clarity that is less tainted by imposed prejudices. He looks at the way attitudes towards 'morality' evolved and the way congenital ideas of morality were heavily colored by the Judaic and Christian traditions.

The Psychopathology of Everyday Life, which appeared first in 1901 and was then expanded in a series of subsequent editions, has proved to be one of Freud's most popular works, and one of his most influential during his lifetime. It was here that he proposed that many slips and errors of memory common to the average man in everyday life actually signals unconscious issues that beset the individual, and, if examined, can be extremely revealing.

The Roman Republic is one of the most breathtaking civilizations in world history. Between roughly 500 BCE to the turn of the millennium, a modest city-state developed an innovative system of government and expanded into far-flung territories across Europe, Northern Africa, and the Middle East. This powerful civilization inspired America's founding fathers, gifted us a blueprint for amazing engineering innovations, left a vital trove of myths, and has inspired the human imagination for 2,000 years.

First published in 1930, Civilization and Its Discontents is one of the most influential works of pioneering psychologist Sigmund Freud. Focusing on the tension between the primitive drives of the individual and the demands of civilization for order and conformity, Freud draws upon his psychoanalytic theories to explain the fundamental structures, conflicts, and consequences of society.

Here are three key works by Sigmund Freud which, published in the first decades of the 20th century, underpinned his developing views and had such a dramatic effect on world society. In the uncompromising Three Essays on the Theory of Sexuality (1905), he declared that 'sexual aberrations' are not limited to the insane but exist in 'normal' people to a greater or lesser degree. The three essays are divided between sexual perversions, childhood sexuality and puberty.

One of the most complicated and advanced computers on Earth can't be purchased in any store. This astonishing device, responsible for storing and retrieving vast quantities of information that can be accessed at a moment's notice, is the human brain. How does such a dynamic and powerful machine make memories, learn a language, and remember how to drive a car? What habits can we adopt in order to learn more effectively throughout our lives? The answers to these questions are merely the tip of the iceberg in The Learning Brain.

This collection of 11 wide-ranging lectures which appeared originally in 1933, was based on lectures previously given when Jung was in the process of absorbing a considerable period of study of Eastern religions, Gnosticism and other religious sources. It was a time, according to the translator Cary F. Baynes, ‘when the Western world stands on the verge of a spiritual rebirth...after a long period of outward expansion, we are beginning to look inside ourselves once more.’

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.

"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.

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."

Man and His Symbols owes its existence to one of Jung's own dreams. The great psychologist dreamed that his work was understood by a wide public, rather than just by psychiatrists, and therefore he agreed to write and edit this fascinating book. Here, Jung examines the full world of the unconscious, whose language he believed to be the symbols constantly revealed in dreams.

Historians universally agree that Thucydides was the greatest historian who has ever lived, and that his story of the Peloponnesian conflict is a marvel of forensic science and fine literature. That such a triumph of intellectual accomplishment was created at the end of the fifth century B.C. in Greece is, perhaps, not so surprising, given the number of original geniuses we find in that period. But that such an historical work would also be simultaneously acknowledged as a work of great literature and a penetrating ethical evaluation of humanity is one of the miracles of ancient history.