Aristotle was the first philosopher to write ethical treatises. His best-known work in this field, The Nicomachean Ethics, consists of 10 books addressing the question of how the individual should best live. For Aristotle, ethics seeks to determine what makes a virtuous character possible, which is essential for a state of well-being. He describes a sequence of necessary steps to achieve this, such as righteous actions that promote the development of the right habits. He examines the moral virtues and their corresponding vices, like courage versus fear.

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.  

A landmark of Enlightenment thought, Hume's An Enquiry Concerning Human Understanding is accompanied here by two shorter works that shed light on it: A Letter from a Gentleman to His Friend in Edinburgh, Hume's response to those accusing him of atheism, of advocating extreme skepticism, and of undermining the foundations of morality; and his Abstract of A Treatise of Human Nature, which anticipates discussions developed in the Enquiry.

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.

Often considered the foundation of political liberalism, John Locke's Two Treatises of Government was first published anonymously in 1689, in the wake of England's Glorious Revolution. In The First Treatise of Government, Locke refutes the idea of divine monarchy, while The Second Treatise of Government articulates Locke's philosophy of government, which he based upon his theories of natural rights and the social contract.