Throughout history philosophers have sought to define, understand, and delineate concepts important to human well-being. One such concept is "knowledge." Many philosophers believed that absolute, certain knowledge, is possible—that the physical world and ideas formulated about it could be given solid foundation unaffected by the varieties of mere opinion.

Here is a grotesque and carnivalesque collection of exuberant, fantastical stories that takes us from the ancient world through to the European Renaissance. At the heart of these tall tales are the giant Gargantua and his equally seismic son, Pantagruel. Containing magical adventures, maniacal punning, slapstick humor, erudite allusions, and just about any bodily function one can think of, here is quite possibly the zaniest, most risqué book ever written.

Assembled from notes and jottings left unpublished at the time of the author’s death, The Book of Disquiet is a collection of aphoristic prose-poetry musings on dreams, solitude, time and memory. Credited to Pessoa’s alter ego, Bernardo Soares, who chronicles his contemplations in this so-called "factless" autobiography, the work is a journey of one man’s soul and, by extension, of all human souls that allow their minds and hearts to roam far and free.

First published in 1621, and hardly ever out of print since, it is a huge, varied, idiosyncratic, entertaining and learned survey of the experience of melancholy, seen from just about every possible angle that could be imagined. The Anatomy of Melancholy, presented here with all the original quotations in English, is, at last, available on audiobook in its entirety.

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.

Here are three important but very different Dialogues from the Middle Period. Symposium, the most well-known in this collection, is concerned with the theme of love. In the house of Agathon, a group of friends - each very different in personality and background - meet to consider and discuss various kinds of love. Each one, Phaedrus, Pausanias, Eryximachus, Aristophanes (the playwright) and Agathon (a prize-winning tragic poet), presents his particular view in a short discourse.

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.

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.

Winner of the 1973 National Book Award, Gravity's Rainbow is a postmodern epic, a work as exhaustively significant to the second half of the 20th century as Joyce's Ulysses was to the first. Its sprawling, encyclopedic narrative and penetrating analysis of the impact of technology on society make it an intellectual tour de force.

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.'