Foundations of Democracy (Athens)
Pericles's Funeral Oration (Thucydides)
Plato, Apology
Aristotle, Republic (Book Three)

Foundations of Democracy (Rome)
Cicero, Of the Republic
Marcus Aurelius, Meditations

Foundations of Democracy (Enlightenment)
Thomas Hobbes, Leviathan 
John Locke, Second Treaty on Civil Government
Rousseau, The Social Contract
Montesquieu, The Spirit of Laws

Writings on Early Democratic Values (American Ideology)
Tocqueville, Democracy in America

British Documents (American Ideology)
Magna Carta
English Bill of Rights
Mayflower Compact

Seminal American Documents (American Ideology)
The Declaration of Independence
Articles of Confederation
Virginia Plan
New Jersey Plan

Modern Speeches
Lincoln's Gettysburg Address