In 212 c. e., by virtue of an edict now known as the Antonine Constitution, the em­peror Caracalla extended citizenship to nearly all free-born residents of the Roman empire.[1]

In so doing, he transformed not only his own but the ideal of empire and, indeed, of statehood in Europe ever after. And yet, despite what might seem the self-evident importance of his action, much about it remains obscure, not least its date, its motivation, and its effects in legal and social relations.

The form of influence exercised by the Antonine Constitution was shaped in absolutely essential ways by the fashion in which it was known. Until the first dec­ade of the twentieth century, the actual wording of the Constitution was unknown, as was the justification offered by Caracalla for his extraordinary action. Instead, the Constitution was known and discussed in light of a number of references to it in legal, historical and later homiletic literatures.^[2] This Introduction therefore falls into three parts. The first surveys the range of legal and ideological contexts in which the Constitution was cited between the sixteenth and eighteenth centuries, from the dawn of Europe’s extra-European imperial ambitions to the writing of the Code Napoleon. The second turns to the subsequent phase in the history of the Constitution, to wit, that which unfolded after the discovery of an ancient copy of the text itself. The final offers one vision of the landscape of legal theory to which the Antonine Constitution, its history and the project here published pertain.