that Tertullian13 refers to the Gnostic systems as “sacramenta haereticarum idearum,” while St. Augustine repeatedly applies the term to the external worship of God and to sacrifice in general.14 It was reserved for the Schoolmen, notably Peter Lombard and St. Thomas, to define the term Sacrament, and to restrict its use to certain rites.15 .—Generally speaking, a Sacrament is, as we have seen, “a symbol of a sacred and mysterious thing.”
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