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.

The Mediums’ Book is not addressed to materialists, who must be brought from materialism to spiritualism, if at all, by their personal ascertainment of the reality of the modern spiritist "manifestations" and by the proof they give of the continued existence of the souls of the deceased men and women by whom they are produced. 

Jonathan Edwards was a Protestant theologian and a leading revivalist preacher during the Great Awakening. Edwards wrote Freedom of the Will in the 18th century while working as a missionary to a tribe of Housatonic Native Americans in Massachusetts. He carefully drew out the differences of thought between the Calvinist and Arminian theologies and sided with the Calvinist views on humanity's will. Edwards sought to understand God's foreknowledge and how it related to free will and the ability to choose between good and evil.

Born out of the political turmoil of the English Civil War, Leviathan stands out as one of the most in influential political and philosophical texts of the 17th century. It argues for the restoration of the monarchy in light of the republic and calls for a commonwealth ruled by an authoritative, autocratic figure with absolute sovereignty. This would put an end to all controversy, war, and fear and establish peace via social contract.

David Hume's Dialogues Concerning Natural Religion had not yet been published when he died in 1776. Even though the manuscript was mostly written during the 1750s, it did not appear until 1779. The subject itself was too delicate and controversial, and Hume's dialectical examination of religious knowledge was especially provocative. What should we teach young people about religion? The characters Demea, Cleanthes, and Philo passionately present and defend three sharply different answers to that question.

A Pluralistic Universe by the philosopher and psychologist William James (1842-1910) is based on a series of lectures held at Oxford University in 1908. James is mainly concerned with the nature of relations, stating the possibility of external relations which were excluded from monistic idealism. James maintains that we are guided by beliefs that we attempt to justify in order to keep our beliefs going. 

Published in 1748, An Enquiry Concerning Human Understanding is Scottish empiricist philosopher David Hume's distillation of his mature philosophy. Addressing themes including the limits of human understanding, the compatibility of free will with determinism, weaknesses in the foundations of religion, and the appeal of skepticism, An Enquiry Concerning Human Understanding is Hume's attempt to revise and clarify the ideas of his earlier A Treatise of Human Nature.

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.’

The foundation for all modern economic thought and political economy, The Wealth of Nations is the magnum opus of Scottish economist Adam Smith, who introduces the world to the very idea of economics and capitalism in the modern sense of the words.

Plagued with doubt and uncertainty in sensory knowledge, Descartes is struck with the idea that everything he knows is false. He considers the possibility that he has been deceived by an 'evil demon' and is left with nothing to lean on, until he arrives at the phrase 'cogito ergo sum' ('I think, therefore I am'). Among the most quoted philosophical works in history, Meditations on First Philosophy and Discourse on the Method together display the full workings of Descartes' skeptical method and the formation of his famous phrase. 

Two contrasting reflections by Aristotle which cover very particular ground. In 'On the Soul', Aristotle presents his view of the 'life essence' which, he argues, is possessed by living things whether plants, animals or humans. Not a 'soul' in the generally accepted Western use of the term, this 'soul', he says, is a life force that is indivisible from the organism that possesses it.

The front cover of the second edition of Language, Truth and Logic carried this statement in capital letters: ‘THE CLASSIC TEXT WHICH FOUNDED LOGICAL POSITIVISM - AND MODERN BRITISH PHILOSOPHY.’ It was a bold statement, but the book, first published in 1936 when A. J. Ayer was just 25 and a lecturer on philosophy at Christ Church, Oxford, drew unstinting praise from leading figures in the field, including Bertrand Russell.

John Stuart Mill (1808-1873) was a torchbearer for liberal thought in the 19th century, including liberty of the individual and freedom of speech, and he championed women's suffrage in Parliament. A remarkable man - he learned Greek aged three and at eight had read Herodotus, Xenophon and Plato - he campaigned all his life for a just society. These two essays are his key works.

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.

David Hume (1711-1776) was the most important philosopher ever to write in English as well as a master stylist. This volume contains his major philosophical works. A Treatise of Human Nature (1739–1740), published while Hume was still in his twenties, consists of three books on the understanding, the passions, and morals.