He commenced his great work on the textual criticism of the Scriptures; and at the instigation of his friend Ambrosius, who provided him with the necessary amanuenses, he published his commentaries on the Old Testament and his dogmatic investigations.
Wellhausen's briefer work (3rd ed., 1898) is especially suggestive for textual criticism.
Much the same applies to Bp Westcott's Gospel according to St John (1882), devotionally so attractive, and in textual criticism excellent.
In dealing, therefore, with the textual criticism of the Old Testament it is necessary to determine the period at which the text assumed its present fixed form before considering the means at our disposal for 'controlling the text when it was, so to speak, in a less settled condition.
In the use of the ancient versions for the purposes of textual criticism there are three precautions which must always be observed; we must reasonably assure ourselves that we possess the version itself in its original integrity; we must eliminate such variants as have the appearance of originating merely with the translator; the remainder, which will be those that are due to a difference of text in the MS. (or MSS.) used by the translator, we must then compare carefully, in the light of the considerations just stated, with the existing Hebrew text, in order to determine on which side the superiority lies."