Many Greek manuscripts of the New Testament after the eighth and ninth centuries mark the beginning of the lections with the word ἀρχή or ἀρ or χʹ/ ἀρ  and the end with the word τέλος or τέ or λ/τέ inserted into the text, but written in coloured, commonly vermillion ink.

Textual criticism is the process by which it is sought to determine the original text of a document or a collection of documents, and to exhibit it, freed from all the errors, corruptions, and variations which it may have accumulated in the course of its transmission in the course of its transmission by successive copyings.

We do not have the original manuscripts of the New Testament. As careful as copyists may be, when a book is copied by hand over nineteen hundred years, mistakes are bound to happen.

By collecting and comparing and weighing the variations of the text found in the New Testament manuscripts to which we have access, New Testament Textual Criticism aims at

1. bringing back that text originally written by the authors of the New Testament, so far as may be, to the condition in which it stood in the sacred autographs;
2. removing all spurious additions, if such be found in our present printed copies;
3. restoring whatsoever may have been lost or corrupted or accidentally changed in the lapse of nineteen hundred years.