The preface to the 1789 Book of Common Prayer says, "this Church is far from intending to depart from the Church of England in any essential point of doctrine, discipline, or worship...further than local circumstances require." There were some notable differences. For example, in the Communion service the prayer of consecration follows mainly the Scottish orders derived from 1549 and found in the 1764 Book of Common Prayer. The compilers also used other materials derived from ancient liturgies especially Eastern Orthodox ones such as the Liturgy of St. James. An epiclesis or invocation of the Holy Spirit in the eucharistic prayer was included, as in the Scottish book, though modified to meet reformist objections. Overall however, the book was modelled on the English Prayer Book, the Convention having resisted attempts at more radical deletion and revision. The 1789 American BCP reintroduced explicit sacrificial language in the Prayer of Consecration by adding the words "which we now offer unto Thee", after "with these thy holy gifts" from the 1549 BCP. The insertion undid Cranmer's rejection of the Eucharist as a material sacrifice by which the Church offers itself to God by means of the very same sacrifice of Christ but in an unbloody, liturgical representation of it. This reworking thereby aligned the church's eucharistic theology more closely to that of the Roman Catholic and Orthodox churches.