In these four dialogues, Plato develops the Socratic belief in responsibility for one's self and shows Socrates living and dying under his philosophy. In Euthyphro, Socrates debates goodness outside the courthouse, Apology sees him in court, rebutting all charges of impiety, in Crito, he refuses an entreaty to escape from prison, and in Phaedo, Socrates faces his impending death with calmness and skillful discussion of immortality.

Aristotle's Poetics (335 BCE) is the earliest surviving work of dramatic theory and first surviving philosophical treatise on dramatic or literary theory. The work begins with a preliminary discourse on tragedy, epic poetry, and comedy as the chief forms of imitative poetry. By "imitative", Aristotle means the imitation of action in words as a creative process. He distinguishes comedy, tragedy, the satyr play, lyric poetry, and epic poetry by their differences in musical rhythm, harmony, meter, melody, nature of the characters, and the manner in which the narrative is presented.

Epictetus, a Greek stoic and freed slave, ran a thriving philosophy school in Nicropolis in the early second century AD. His animated discussions were celebrated for their rhetorical wizardry and were written down by Arrian, his most famous pupil. Together with the Enchiridion, a manual of his main ideas, and the fragments collected here, The Discourses argue that happiness lies in learning to perceive exactly what is in our power to change and what is not, and in embracing our fate to live in harmony with god and nature.

Written between A.D. 413 and 426, The City of God is one of the great cornerstones in the history of Christian thought, a book which is vital to the understanding of modern Western society. Augustine originally intended it to be an apology for Christianity against the accusation that the Church was responsible for the decline of the Roman Empire, which had occurred just three years earlier. Indeed, Augustine produced a great amount of evidence to prove that paganism was responsible for this event. However, by the time the work was finished, the book had taken on a larger theme.

Roman statesman and philosopher Marcus Tullius Cicero wrote on a wide range of subjects, from Greek philosophy to moral duty to friendship. Though he considered philosophy secondary to politics and often used his writings for explicit political ends, his work has nevertheless been widely read for over two thousand years and has influenced everything from the culture of the Renaissance to the ideals of the founding fathers of the United States.

One of Nietzsche’s earliest works, The Birth of Tragedy (1872) is a remarkable source of inspiration. It is here that the philosopher expresses his frustration with the contemporary world and urges man to embrace Dionysian energy once more. He refutes European culture since the time of Socrates, arguing that it is one-sidedly Apollonian and prevents man from living in optimistic harmony with the sufferings of life.

The second edition of Five Dialogues presents G.M.A. Grube's distinguished translations, as revised by John Cooper for Plato's complete works. It includes: Euthyphro, Apology, Crito, Meno, and Phaedo.

The Nature of Things was written in the 1st century BC by Roman polymath Lucretius. It is written as a didactic poem, and explains Epicurean physics.

By calling everything into doubt, Descartes laid the foundations of modern philosophy. With the celebrated words "I think therefore I am," his compelling argument swept aside ancient and medieval traditions. He deduced that human beings consist of minds and bodies; that these are totally distinct "substances"; that God exists and that He ensures we can trust the evidence of our senses.

It can be said of very few books that the world was changed as a result of its publication - but this is certainly the case of Capital: A Critique of Political Economy by Karl Marx (1818-1883). Volume 1 appeared (in German) in 1867, and the two subsequent volumes appeared at later dates after the author's death - completed from extensive notes left by Marx himself.