SACRO. — Ancient Latin sakros, later sacer, from sancire, whether by religion or by law, is that which is considered inviolable and therefore forbidden to profane use. This interdiction may depend upon an unwritten sacred motive, handed down by tradition within the social group, which cannot violate it without harm.
The s. is ambivalent, inasmuch as it may harm anyone who approaches it without the proper lustral precautions, which must be used whenever the s. and the profane come into contact; whereas it is a source of well-being for anyone who presents himself before it in a state of holiness, either because he himself is invested with it (king, priest), or because he has prepared himself for it through the prescribed purifications. The episode of Uzzah is well known from the Bible (II Sam. 6:6–8), when he fell lifeless because he had supported the holy Ark with his hand as it was in danger of falling owing to a false step by the oxen that were pulling II. It is likewise familiar from catechetical instruction that anyone who approaches to receive a Sacrament of the living without possessing the state of Grace receives spiritual death rather than an increase of life.
Holy, on the other hand, is that which is recognized as such following a sanction by the group or by its representative. In ancient Rome, the tribune of the plebs enjoyed a sacrosanct authority, because the sacredness—that is, the inviolability—of his person was guaranteed by the collective oath sworn by the plebs in his favor, and his holiness was a consequence of the official recognition that the State, albeit reluctantly, was obliged to grant him. That this recognition assumed a religious form may be inferred from Livy (III, 55), who, after recounting the end of the decemvirate, states that the new tribunes were confirmed by religious ceremonies: «quum religione inviolatos eos, tum lege etiam fecerunt».