This thesis represents an attempt to comprehend what is implied by or included in the idea of commonwealth. The principal authority on this subject is taken to be James Harrington, author of The Commonwealth of Oceana [1656]. But Harrington's political thinking drew upon the political experiences of other times and places: Athens, Rome, and Florence. We will consider the various insights Harrington took from his reading and his travels: civic virtue, an agrarian law, mixed government, checks and balances, tolerance. An attempt will be made to complement Harrington's political ideas by linking them with a theory of political judgment analogous to Aesthetic and Teleological judgment, as elaborated by Immanuel Kant in The Critique of Judgement . And, finally, Harrington's idea of commonwealth is shown to be consistent with a theory of rights, as institutionalized in the English Bill of Rights [1693], the American Declaration of Independence and subsequent amendments to the American Constitution and the Universal Declaration of Human Rights.