Schopenhauer was just 30 when his magnum opus, Die Welt als Wille und Vorstellung, a work of considerable learning and innovation of thought, first appeared in 1818.

Much to his chagrin and puzzlement (so convinced was he of its merits), it didn't have an immediate effect on European philosophy, views and culture. It was only decades later that it was recognised as one of the major intellectual landmarks of the 19th century.

The essays in The Two Fundamental Problems of Ethics have a rather special place in Schopenhauer’s work, both being written as entries to Scandinavian philosophy competitions, one in Norway and one in Sweden.

Published in 1797, the Critique of Pure Reason is considered to be one of the foremost philosophical works ever written. In the Critique of Pure Reason, Immanuel Kant explores the foundation of human knowledge and its limits, as well as man's ability to engage in metaphysics.

Parerga means 'supplementary to a main work', and Paralipomena suggests a further supplement, but these two books were anything but a casual addition to his major opus, The World as Will and Idea. For a start, it was the publication of Parerga and Paralipomena in 1851 which brought Schopenhauer to the attention of the general public, decades after The World as Will and Idea first appeared.  

'The two foes of human happiness are pain and boredom.' Arthur Schopenhauer (1788-1860) was one of the most influential philosophers of the 19th century because his humanistic, atheistic, if pessimistic views chimed with a new secularism that was emerging from a Western society dominated by religion. Despite his rather forbidding image (and a few outdated views), he is one of the most approachable German philosophers, and this is certainly evident in these two key works, The Wisdom of Life and Counsels and Maxims.

First proposed more than 200 years ago, Schopenhauer's extraordinarily prescient metaphysics - if understood along the lines thoroughly elucidated and substantiated in this volume - offer powerful answers not only to the paradoxes of quantum mechanics, but also to modern philosophical dilemmas such as the hard problem of consciousness - which plagues mainstream physicalism - and the subject combination problem - which plagues constitutive panpsychism 

A classic guide to tricks and tactics for winning arguments, with commentary on the use of and defense against each tactic. The best summary of this audiobook is "being right doesn’t mean you’re gonna win, and this is why". It’s the ultimate guide to spotting the many different kinds of bull people pull in order to win over the crowd, rather than argue the point at hand. There’s very few of them that don’t immediately bring examples to mind, and having it laid out clearly like this is the perfect armour to stop people derailing you. 

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.

Philosophical Investigations was published in 1953, two years after the death of its author. In the preface written in Cambridge in 1945 where he was professor of philosophy he states: ‘Four years ago I had occasion to re-read my first book (the Tractatus Logico-Philosophicus) and to explain its ideas to someone. It suddenly seemed to me that I should publish those old thoughts and the new ones together: that the latter could be seen in the right light only by contrast with and against the background of my old way of thinking.’

This Leibniz collection contains some of the philosopher’s most important works and ideas, spans three decades and illuminates the fascinating intellectual journey undertaken by him in his quest for truth. A prodigious polymath, Leibniz was a mathematician, philosopher, physicist and statesman and engaged with a sweeping range of ideas and disciplines, striving throughout his life to be at the cutting edge of scientific thinking. These Principal Essays are arranged in chronological order. 

Kant's Prolegomena, although a small book, is without doubt the most important of his writings, writes the translator, Paul Carus. Prolegomena means, literally, prefatory or introductory remarks, and it furnishes us with a key to his main work, The Critique of Pure Reason; in fact, it is an extract containing all the salient ideas of Kant's system. It approaches the subject in the simplest and most direct way and is therefore best adapted as an introduction into his philosophy. 

John Locke and his works - particularly An Essay Concerning Human Understanding - are regularly and rightly presented as foundations for the Age of Enlightenment. His primary epistemological message - that the mind at birth is a blank sheet waiting to be filled by the experiences of the senses - complemented his primary political message: that human beings are free and equal and have the right to envision, create and direct the governments that rule them and the societies within which they live.

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.

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.

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.