 Although the term “loyalty” has its immediate philological origins in Old French, its older and mostly abandoned linguistic roots are in the Latin lex (law). Nevertheless, dimensions of the phenomenon that we now recognize as loyalty are as ancient as human association, albeit often manifested in its breaches (disloyalty, betrayal). The Old Testament writers were often occupied with the fickleness of human commitments, whether to God or to each other. To characterize such fickleness they tended to use the language of (un)faithfulness, though nowadays we might be inclined to use the more restricted language of (in)fidelity, which has regard to specific commitments. In medieval to early modern uses of the term, loyalty came to be affirmed primarily in the oath or pledge of fealty or allegiance sworn by a vassal to his lord. That had an interesting offshoot as monarchical feudalism lost sway: loyal subjects who were distressed by the venality of sitting sovereigns found it necessary—as part of their effort to avoid charges of treason—to distinguish their ongoing loyalty to the institution of kingship from their loyalty to a particular king.