Phillips is more the bibliographer and cataloguer, collecting names and titles; Winstanley is the amateur literary historian, seeking out the verse itself, arranging it in chronological order, and trying to pass judgment upon it.[5]
As a bibliographer Phillips was exceedingly inaccurate and "the _Theatrum_ was a hasty, careless piece of hack work," whose convenience was seriously damaged by a poor organization which alphabetizes the poets in four sections by their first names, with no last name index. His source materials were of the easiest and most superficial kind.[6] Both Phillips and Winstanley misunderstood Kirkman's method of listing anonymous plays and this, as Langbaine notes in the Preface to _Momus_, led "_both these charitable kind Gentlemen_" to find "_Fathers for them, by ranking each under the Authors Name that preceded them in the former Catalogues_"([A3r]).[7]
Although he acknowledged all three men in his Preface and mentions them each about thirty times in the _Account_, it was Kirkman who was most admired by Langbaine and of most use to him. Kirkman's _Catalogue_ of 1671, "_the_ first ... _printed of any worth_," was the principal source of _Momus_, and it, in turn, was based on a catalogue which Kirkman made and published ten years previously.[8] The format of Kirkman's 1671 catalogue followed the general format of his earlier catalogue and of several earlier play lists[9] by arranging the plays alphabetically by title and with some haphazard attempt at chronological order as well, but, as Langbaine described it, "promiscuously _as to those of_ Authors" except for "Shakespeare, Fletcher, Johnson, _and some others of the most voluminous Authors_," whose works were inserted in first place ([A3r]). The catalogue listed eight hundred and eight plays, and its principal orientation was most likely not scholarly but commercial, to list the books which Kirkman had for sale.[10] Nevertheless, Kirkman argued for the completeness of the second catalogue:
I really believe there are no more [plays], for I have been these twenty years a Collector of them, and have conversed with, and enquired of those that have been Collecting these fifty years. These, I can assure you, are all in Print, for I have seen them all within ten, and now have them all by me within thirty.[11]