In the late 1st century AD, cremation was such a commonplace that Tacitus could refer to it as "Romanus mos" ("the Roman Way"). According to Plutarch, king Numa Pompilius had forbidden cremation; so perhaps in at least partial obedience to this prohibition, and perhaps on the understanding that "a part implies the whole", a complete finger was sometimes cut from the corpse before cremation and buried separately, unburnt, to complete the household's purification, return the deceased to mother Earth and make the grave inviolable. The practice, known as "os resectum" ("cut-off bone") is attested by literary sources (Cicero, "de legibus", 2.55; Varro, "lingua Latina", 5.23; Pauly Festus 135 L.