Philosophy
Free to read here, from Project Gutenberg.
The Prince
Second Treatise of Government
Thus Spake Zarathustra: A Book for All and None
Beyond Good and Evil
The Republic
On Liberty
Apology
The Nicomachean ethics of Aristotle
The Problems of Philosophy
The Critique of Pure Reason
The Communist Manifesto
The Poetics of Aristotle
Ethics
Discourse on the Method of Rightly Conducting One's Reason and of Seeking Truth in the Sciences
Democracy and Education: An Introduction to the Philosophy of Education
Utilitarianism
An Enquiry Concerning Human Understanding
Tractatus Logico-Philosophicus
A System of Logic, Ratiocinative and Inductive
The Antichrist
Politics: A Treatise on Government
Euthyphro
A Treatise of Human Nature
Also sprach Zarathustra: Ein Buch für Alle und Keinen
Theaetetus
Considerations on Representative Government
Ion
The Case of Wagner, Nietzsche Contra Wagner, and Selected Aphorisms.
An Enquiry Concerning the Principles of Morals
Laughter: An Essay on the Meaning of the Comic
The Analysis of Mind
A System of Logic, Ratiocinative and Inductive (Vol. 1 of 2)
Dialogues Concerning Natural Religion
Autobiography
Mysticism and Logic and Other Essays
Discours de la méthode
A Treatise Concerning the Principles of Human Knowledge
The Approach to Philosophy
The Categories
Aesthetical Essays of Friedrich Schiller
Kritik der reinen Vernunft
On the Improvement of the Understanding
Our Knowledge of the External World as a Field for Scientific Method in Philosophy
Theologico-Political Treatise — Part 1
Aristotle on the art of poetry
Symbolic Logic
Moral Principles in Education