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.

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 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.

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.

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.