Critique of Judgement was published in 1790 and is divided into two parts, the Critique of Aesthetic Judgement and the Critique of Teleological Judgement. Our ‘judgements of taste’, as Kant describes our aesthetic judgements, have both a personal and a universal function: personal, because we have a subjective aesthetic response to the ‘agreeable’, the ‘beautiful’, the ‘sublime’ and the ‘good’; but also there is a ‘universal’ aspect because our aesthetic response has a ’disinterested’ element. This brings under Kant’s spotlight, for example, the concept of beauty and the perception of beauty.

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.

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.

Groundwork of the Metaphysics of Morals (1785) is the first of Immanuel Kant's mature works on moral philosophy and remains one of the most important in the field. Kant examines the core concepts and principles of moral theory, showing that they are normative for rational agents. He aspires to lay bare the fundamental principle of morality and prove that it applies to us. Kant offers the argument that the rightness of an action is determined by the character of the principle that a person chooses to act upon.

The Critique of Practical Reason was published in 1788, seven years after Immanuel Kant's major work, Critique of Pure Reason. In it, Kant sets out his moral philosophy - and it proved a seminal text in the history of the subject. He argues that the summum bonum (the highest good) of life is that rather than just pursuing happiness, people should inhabit a moral dimension that enables them to deserve the happiness that God can give. Though much shorter than Critique of Pure Reason, this is the sourcebook for Kant’s ethical doctrines.

Immanuel Kant's Fundamental Principles of the Metaphysics of Morals, first published in 1785, lays out Kant's essential philosophy and defines the concepts and arguments that would shape his later work. Central to Kant's doctrine is the categorical imperative, which he defines as a mandate that human actions should always conform to a universal, unchanging standard of rational morality.

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.

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.

Continuing where Thus Spoke Zarathustra left off, Nietzsche's controversial work Beyond Good and Evil is one of the most influential philosophical texts of the 19th century and one of the most controversial works of ideology ever written. Attacking the notion of morality as nothing more than institutionalised weakness, Nietzsche criticises past philosophers for their unquestioning acceptance of moral precepts. Nietzsche tried to formulate what he called "the philosophy of the future".

A Treatise of Human Nature is the first work ever published by David Hume, a man who revolutionized our understanding of philosophy. Hume was an advocate of the skeptical school of philosophy and a key figure in the Scottish Enlightenment. He looks at the nature of human experience and cognition, showing that philosophy and reason can only be reflections of our nature.

Aristotle's Metaphysics was the first major study of the subject of metaphysics - in other words, an inquiry into 'first philosophy', or 'wisdom'. It differs from Physics which is concerned with the natural world: things which are subject to the laws of nature, things that move and change, are measurable. In Metaphysics, the study falls on 'being qua being' - being insofar as it is being; the causes and principles of being, the causes and principles of substances.

Being and Time was published in 1927 during the Weimar period in Germany, a time of political, social and economic turmoil. Heidegger himself did not escape the pressures and his nationalism, and undeniable anti-Semitism in the following decades cast a shadow over the man, but not the work. Being and Time is not coloured by expressions of his later views (unlike other writings) and remains an outstanding document.

Kant is arguably the most influential modern philosopher, but also one of the most difficult. Roger Scruton tackles his exceptionally complex subject with a strong hand, exploring the background to Kant's work and showing why the Critique of Pure Reason has proved so enduring.

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.

Benedict de Spinoza's Ethics, first published in 1677, constitutes a major systematic critique of the traditional and religious foundations of philosophical thought. In it, Spinoza follows a logical step-by-step format consisting of definitions, axioms, propositions, proofs, and corollaries to create a comprehensive inquiry into the truth about God, nature, and humans' place within the universe. From these broad metaphysical themes, Spinoza derives what he considered to be the highest principles of religion and society and lays out an ethical system in which reason is the supreme value.