Library E. W. Bullinger Number in Scripture
Part II — Spiritual Significance
Fifty-one
This is the number of Divine revelation,
for there are 24 books in the Old Testament,
and 27 books in the New Testament,
making 51 in all.
This is, of course, reckoning the Divine separation of the books, as exhibited in the MSS, which form our only authority, and not reckoning according to man's manipulation of them; for both Jewish and Gentile fancies and reasonings make quite a different and conflicting number. See pp. 25, 26.
E. W. Bullinger, Number in Scripture: Its Supernatural Design and Spiritual Significance, fourth edition revised (London: Eyre & Spottiswoode, 1921). Public domain. Sectioned HTML transcription via Levend Water; bibliographic record and page scan of the 1894 edition from the Claremont School of Theology collection via Internet Archive.