The dilemma of providing simultaneous and equally persuasive justifications of both dominium and imperium bedevilled theorists of real property and of maritime law. The dilemma was not necessarily insoluble, because there was no paradox involved in making such parallel claims to property and jurisdiction: the one did not necessarily threaten the other, though, as the Spanish Monarchy had discovered decades before the English and Scottish Crowns would, the two claims were not dependent upon one another, and each needed a separate and distinct argument. A more intractable dilemma arose from the tension between the competing demands of two overwhelmingly desirable but ultimately irreconcilable goals, liberty and empire. A variety of solutions to this dilemma had emerged by the later seventeenth century and, as William Petty noted in the 1680s, it may have been more apparent than real. However, for the classical – above all, Roman – historical and moral traditions within which the majority of early-modern British theorists had been educated, libertas and imperium remained seemingly incompatible values. This was hardly confined to those who asserted the primacy of Roman moral and political thought as a means of contemporary self-understanding. So widespread was knowledge of classical history, among the generally educated as well as the more technically learned, that the problem of how to achieve empire while sustaining liberty became a defining concern of British imperial ideology from the late sixteenth century onwards.