Niccolò Machiavelli 
Discourses on the First Decade of Titus Livius 
With linked Table of Contents

The Discorsi is a series of lessons on how a republic should be started and structured, including the concept of checks and balances, the strength of a tripartite structure, and the superiority of a republic over a principality. Its lessons are as valid today as they were six centuries ago and clear applications of his practical political philosophy can be found in the governments of many democracies today.