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.

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.

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.

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.

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.

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.

As the 20th century drew to a close, the Austrian psychologist Alfred Adler (1870-1937) was perhaps the least known of the prominent figures of his time - in particular Sigmund Freud and Carl Gustav Jung - and yet he continues to be a figure of influence in the 21st century. His school of ‘individual psychology’ involved a holistic approach to the study of the individual, with a key focus on the way each person viewed the world, especially regarding their concerns of inferiority.

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.’

Alfred Adler was an Austrian physician, psychotherapist, and one of the founding fathers of modern psychology. In Understanding Human Nature, (1928), Adler sets out to acquaint the general public with the basics of Individual Psychology, which holds that the driving force of human behavior is the individual’s striving for power, partly to compensate for feelings of inferiority. The purpose of the book is to identify mistaken behaviors and show how they undermine healthy relationships, in order to gently guide the individual towards adjustment.

Perhaps one of the most revolutionary works of philosophy ever presented, The Phenomenology of Spirit is Hegel's 1807 work that is in numerous ways extraordinary. A myriad of topics are discussed, and explained in such a harmoniously complex way that the method has been termed Hegelian dialectic. Ultimately, the work as a whole is a remarkable study of the mind's growth from its direct awareness to scientific philosophy, proving to be a difficult yet highly influential and enduring work.

In this best-selling book, one of America's most distinguished psychologists crystallises the great progress that has been made in the development of the techniques and basic philosophy of counselling. Carl Rogers gives a clear exposition of procedures by which individuals who are being counselled may be assisted in achieving for themselves new and more effective personality adjustments. Contemporary psychology derives largely from the experimental laboratory or from Freudian theory. It is preoccupied with minute aspects of animal and human behaviour or with psychopathology.

The Red Book, published to wide acclaim in 2009, contains the nucleus of C. G. Jung's later works. It was here that he developed his principal theories of the archetypes, the collective unconscious, and the process of individuation that would transform psychotherapy from treatment of the sick into a means for the higher development of the personality.

Immanuel Kant’s Critique of Pure Reason can lay claim to being the most important single work of modern philosophy, a work whose methodology, if not necessarily always its conclusions, has had a profound influence on almost all subsequent philosophical discourse. In this work Kant addresses, in a groundbreaking elucidation of the nature of reason, the age-old question of philosophy: “How do we know what we know?” and the limits of what it is that we can know with certainty.

Collected Papers on Analytical Psychology comprises a selection of key writings and lectures by Carl Gustav Jung produced between 1902 and 1916, which are presented in chronological order. As such they provide a fascinating exposition of the nature and essence of the psychological content of psychoses and neuroses, as explored and discovered by Dr Jung in the early years of his long and distinguished career.

The late Carl Rogers, founder of the humanistic psychology movement, revolutionized psychotherapy with his concept of "client-centered therapy." His influence has spanned decades, but that influence has become so much a part of mainstream psychology that the ingenious nature of his work has almost been forgotten. With a new introduction by Peter Kramer, this landmark book is a classic in its field and a must-listen for anyone interested in clinical psychology or personal growth.