In addition, there are so many quotes from the New Testament in early church documents and commentaries that the entire New Testament could also be assembled from these alone. Not all biblical manuscripts come from orthodox Christian writers. For example, the Gnostic writings of Valentinus come from the 2nd century AD, and these Christians were regarded as heretics by the mainstream church. The sheer number of witnesses presents unique difficulties, but it also gives scholars a better idea of how close modern Bibles are to the original versions.