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.

Sigmund Freud (1856-1939) is remembered as the father of psychoanalysis. Civilization and Its Discontents (1930) is one of his key works, written three decades after his seminal book The Interpretation of Dreams. In it he considers the conflict between the needs of the individual acting both egotistically and altruistically in the pursuit of happiness and the myriad demands of civilised society and the ensuing tensions this clash of needs and demands generates.

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 Gay Science (The Joyful Wisdom) is one of Nietzsche's greatest books. His wonderfully fertile mind roams over mankind, his thoughts, his emotions, his behaviour and his weaknesses with remarkable clarity, with insight - but also with humour!In this work are 383 separate paragraphs, some short, some long, but all singular observations - the epitome of his famous aphoristic style. 'Morality is the herd instinct in the individual.'

The Decline of the West - Volume 1 published in 1917, Volume 2 in 1922 - has exercised and challenged opinion ever since. It was a huge undertaking by Oswald Spengler (1880-1936), formerly an unpublished historian and philosopher who set out to radically reconsider history - the rise and fall of world civilisations and their cultures. His primary view was to reject the established Eurocentric paradigm (ancient/classical, Medieval - and, following the Renaissance - modern) and to take a totally new perspective.

One of Freud's central achievements was to demonstrate how unacceptable thoughts and feelings are repressed into the unconscious, from where they continue to exert a decisive influence over our lives. This volume contains a key statement about evidence for the unconscious and how it works, as well as major essays on all the fundamentals of mental functioning. Freud explores how we are torn between the pleasure principle and the reality principle, how we often find ways both to express and to deny what we most fear and why certain men need fetishes for their sexual satisfaction.

Nietzsche never recovered from his mental breakdown in 1889 and therefore was unable to further any plans he had for the ‘magnum opus’ he had once intended, bringing together in a coherent whole his mature philosophy. It was left to his close friend Heinrich Köselitz and his sister Elizabeth Förster-Nietzsche to go through the remaining notebooks and unpublished writings, choosing sections of particular interest to produce The Will to Power, giving it the subtitle An Attempted Transvaluation of All Values.

The Interpretation of Dreams by Sigmund Freud is one of the most significant books of the 20th century. Though dreams and their role in human consciousness have been a continuing thread in religion and art and life down the centuries, Freud's look at the subject through the prism of his emerging practice and study of psychoanalysis provided a startlingly new and challenging perspective.

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.

The last works completed before Nietzsche's final years of insanity, Twilight of the Idols and The Antichrist contain some of his most passionate and polemical writing. Both display his profound understanding of human nature and continue themes developed in The Genealogy of Morals, as the philosopher lashes out at the deceptiveness of modern culture and morality. Twilight of the Idols attacks European society, Christianity, and the works of Socrates and Plato; The Antichrist explores the history, psychology, and moral precepts of Christianity.

Published first in 1912, Psychology of the Unconscious was one of the most important stepping stones in the development of Jung’s thought and practice. It has a long subtitle: A Study of the Transformations and Symbolisms of the Libido. A Contribution to the History of the Evolution of Thought. This expressed the underlying impetus - a break from the view of the libido and its functions as taught by Sigmund Freud, which Jung had earlier adopted. It was from this point that the two approaches, which came to be known as the Swiss and Viennese schools, emerged.

Imagine a world where the difference between man and machine blurs, where the line between humanity and technology fades, and where the soul and the silicon chip unite. This is not science fiction. This is the twenty-first century according to Ray Kurzweil, the “restless genius” (The Wall Street Journal), “ultimate thinking machine” (Forbes), and inventor of the most innovative and compelling technology of our era.

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.

This series of 28 lectures was given by Sigmund Freud (1856-1939), the founder of psychoanalysis, during the First World War and first published in English in 1920. The purpose of this general introduction was to present his work and ideas - as they had matured at that point - to a general public; and even though there was to be considerable development and change over the ensuing years, these talks still offer a valuable and remarkably approachable entry point to his revolutionary concepts.

This recording contains four important and related works by Heidegger: 'What Is Philosophy', 'What Is Metaphysics', 'On the Essence of Truth' and 'The Question of Being'.