The 2^nd century apostolic writers had a loose connection to the original apostles.  Some of these early 2^nd century writings were occasionally considered part of the canonical biblical writings.  This post-apostolic group lived after the destruction of the Jerusalem Temple in 70 CE.  These authors included Clement of Rome (40-101 CE) and his writings, as well as the so-called Second Letter of Clement, a 2^nd century sermon, but not from Clement.  There also was Ignatius of Antioch (50-117 CE) with his letters, and the 2^nd century Pseudo-Barnabas letter.  From the late 1^st century, the Didache, the Teaching of the Twelve Apostles, has intrigued scholars.  The 2^nd century Shepherd of Hermas, has an apocalyptic document that included visions, commands, mandates, and parables or similitudes.  Theophilus of Antioch (115-180 CE) and Melito of Sardis (+190 CE), an important bishop of Asia Minor, were writing apologists for Christianity.  Clement of Alexandria (150-215 CE) and his pupil Origen (185-254 CE) played an important role in the developing Christian theology in Alexandria.  Justin the martyr (100-165 CE) gave a great description of the Christian activities.  Irenaeus (140-202 CE), a disciple of the martyr Bishop Polycarp of Smyrna, wrote against various early Christian heretics.