The Codex Alexandrinus is a fifth-century Christian manuscript of a Greek Bible, containing the majority of the Greek Old Testament and the Greek New Testament. It is one of the four Great uncial codices. Along with the Codex Sinaiticus and the Vaticanus, it is one of the earliest and most complete manuscripts of the Bible. Brian Walton assigned Alexandrinus the capital Latin letter A in the Polyglot Bible of 1657. This designation was maintained when the system was standardized by Wettstein in 1751. Thus, Alexandrinus held the first position in the manuscript list.