Various early Christian writers wrote gospels and other books, some of which were canonized as the New Testament canon developed. The Apostolic Fathers were prominent writers who are traditionally understood to have met and learned from Jesus's personal disciples. The Church Fathers are later writers with no direct connection to the disciples (other than the claim to apostolic succession). Early Christian apologists tried to defend Christianity against its critics, especially the Ancient Greek and Roman philosophers. Dates given, if not otherwise specified, are of their writings or bishopric, not of their lives.