Here is A. C. Clark's original (1914) preface to The Primitive Text of the Gospels and Acts (1914):
'The chief result of my investigation has been to show the falsity of the principle brevior lectio potior ['prefer the shorter reading']. This was laid down by Griesbach as a canon of criticism in the words :'Brevior lectio, nisi testium vetustorum et gravium auctoritate penitus destituatur, praeferenda est verbosiori. Librarii enim multo proniores ad addendum fuerunt quam ad omittendum.' ["A shorter reading, unless the authority of the witnesses completely lacks weight and antiquity, is preferable to a verbose one. For a copyist is much more prone to further additions than to make omissions."]
Unless my method is based upon a delusion, this statement has no foundation in facts. I may also observe that it is not so easy to invent as it is to omit.
It will be understood that my work has been almost exclusively confined to the text of Cicero. It was only recently, after I had gained confidence in the use of my method, that, in a spirit of curiosity, I happened to apply it to the text of the Gospels. The results were so surprising that I gave up, for the present, my work upon Cicero, which can only interest a small circle, and devoted myself to this more important inquiry.
I must here state that when I began my investigation, I had not made any study of New Testament criticism. I had been brought up to look on the Revised Text  as final, to smile at persons who maintained the authenticity of St. Mark 16:9-20, or St. John 7:53-8:11, and to suppose that the 'vagaries' of the 'Western' text were due to wholesale interpolation. The object which I had in view was merely to study the mutual relations of the oldest Greek Uncials, notably, the Vaticanus (B), the Sinaiticus (א), and the Alexandrinus (A). I was, however, soon dislodged from this arrogant attitude, and irresistibly driven to very different conclusions. These I can only briefly indicate here, and must refer the reader to my subsequent discussion for the evidence.
Nowhere is the falsity of the maxim brevior lectio potior more evident than in the New Testament. The process has been one of contraction, not of expansion. The primitive text is the longest, not the shortest. It is to be found not in B/א, or in the majority of Greek MSS., but in the 'Western' family, i. e. in the ancient versions and the Codex Bezae (D). If my analysis is sound, we are brought back to an archetype of the four Gospels in book-form, which cannot be later than the middle of the 2nd century. This archetype appears to have contained the passages which have been most seriously suspected by recent critics, e.g. the End of St. Mark and St. John 7:53-8:11.
This statement concerning St. Mark 16:9-20 will appear so startling that I must insert a caveat. I do not pretend to go one step further than I am led by the method which I have followed. The ultimate problems of New Testament autographs do not concern me. I only deal with one set of phenomena, and my starting-point is the text current in the second century. I have made no attempt to acquaint myself with the Synoptic problem, and do not venture to encroach upon the domain of the Higher Criticism. Also, I do not regard my method as a panacea. I am sensible that much must be due to accident and to mere coincidence. It is for the reader to determine, whether the cumulative evidence which I adduce is so great as, in certain cases, to transcend the limits of coincidence.
The results at which I have arrived in the case of the Acts are even more striking. It is here that the problem of the 'Western' recension has been felt most strongly. Thus a recent writer says :
'It is the correct method to study the Western readings in Acts first of all, and to form some kind of judgement on them, and after this to turn to the Gospels and apply to them the conclusions derived from the study of the Acts.' (Lake, The Text of the New Testament, p. 91.)This was not the process which I followed, but the conclusions arrived at in the case of the Acts greatly confirm the results furnished by the study of the Gospels.
It is briefly this, that all our MSS., including D, are descended from an ancestor written not in lines of equal length, as in the case of the Gospels, but in cola and commata, i. e. sense-lines of varying length, such as those found in D. The ordinary text has been developed from this by the frequent omission of lines, followed by modifications in the text. For proof of this statement I must refer the reader to the chapter upon the Acts.
I have not extended my inquiry to other parts of the New Testament, since I found that the Gospels and Acts provided more material than I could deal with in the time at my disposal. It appeared to me from some preliminary observations that the Pauline Epistles must be studied together. It is unnecessary to point out that the Apocalypse is a unique document which must be considered separately.'