P46 is an example of one of the earliest forms of the New Testament; the papyrus codex. While the canon of the New Testament was gradually being formed, different Christian writings were being copied and collected into volumes written on papyrus, such as this codex containing the Epistles of Paul. Only in the fourth century, with the acceptance of Christianity by Constantine, did the New Testament as we know it take form in a single volume. Papyrus was replaced by parchment, then by paper, as manuscripts grew more decorative and eventually gave way to printed books. Below is a simplified timeline showing how the form of the Bible, particularly the New Testament, has evolved over the past two thousand years. (For more on the evolution of the Bible, see the online exhibit, From Papyri to King James).
All books prior to the advent of printing were manuscripts which, as their name implies, were copied by hand. These books, usually penned by professional scribes or highly trained monks, were prone to errors made by the person copying the text. As a result, no two copies of the same book could be expected to contain exactly the same text. When modern editors wish to reconstruct a text as accurately as possible, it is often beneficial to consult the oldest manuscript available, on the presumption that the older the manuscript, the closer it is to the original text.
Because P46 was discovered outside of its archaeological context (it was purchased from antiquities dealers in Egypt), there is no external evidence to help date the codex. Instead, scholars date this, like so many other papyri, using palaeography, the study of writing style. Since handwriting styles change steadily over time, it is possible to give a papyrus a rough date (accurate to within 50 years) by comparing its handwriting to that of other papyri. Using this method, scholars date P46 to the third century AD.
While some may argue for a slightly earlier or later date, no one will dispute that P46 is significantly earlier than the Vatican and Sinaitic Codices (both dating to the fourth century), which had previously been the oldest authorities for the Pauline text. While P46 was copied more than a century after Paul originally wrote his Epistles, this codex is nevertheless the closest that modern scholars have been able to get to Paul's original words.