In his 1730 edition of the Prolegomena to the Greek New Testament, Johann Jakob Wettstein devotes to the issue of conjectural emendation a large part of the Observations and Cautions necessary to the examination of the variant readings of the New Testament. Drawing support from the Church Fathers as well as from renowned modern predecessors, the Amsterdam theologian justifies in this work the reasons for and against the use of conjectures in New Testament Textual Criticism.