Thomas of Ireland's Manipulus florum ("Handful of flowers") belongs to the genre of medieval texts known as florilegia, collections of authoritative quotations that are the forerunners of modern reference works such as Bartlett's Familiar Quotations and The Oxford Dictionary of Quotations. This particular florilegium contains approximately 6000 Latin proverbs and textual excerpts (provided in 5821 entries*) that are attributed to various classical, patristic and medieval authors. Compiled in Paris at the beginning of the 14th century (1306), it survives in over 200 manuscripts and was published in at least 50 editions between 1483 and 1887, making it by far the most widely-disseminated and, presumably, the most influential anthology of Latin quotations produced during the Middle Ages.
The seminal study of the Manipulus was published in 1979 by Mary Rouse and Richard Rouse: Preachers, Florilegia and Sermons: Studies on the 'Manipulus florum' of Thomas of Ireland, PIMS Texts and Studies 47, Toronto: Pontifical Institute of Mediaeval Studies.
Thomas organized the "flowers" that he gathered for this collection under 266 alphabetically-ordered topics, from Abstinencia to Christus (Christus coming at the end in the manuscripts and first two printed editions because the Greek letters Χρς are used for the abbreviation). He also assigned unique reference letters to the individual entries under each topic, doubling the letters when the number of entries for a given topic exceeded 23 (i.e. the number of letters in the Latin alphabet). For example, Vsura b is the second (and last) entry under the shortest topic; because Prudencia siue prouidencia has 24 entries, the twenty-third entry is designated 'z' and the last one is 'ba'; and Mors di is the last entry under the largest topic, with 97 entries. As Thomas explains in his Preface, these reference letters were created to support his cross-referencing system; at the end of nearly all of the topics he provided a reference list which includes similar topics (essentially synonyms and antonyms, such as Temperancia and Gula which are cross-referenced at the end of Abstinencia) and, more usefully, specific entries of related interest under unrelated topics. According to the Rouses, this combination of an alphabetized subject listing and a cross-referencing system represents the cutting edge of information technology at the time of its compilation. They also noted the remarkable stability of the manuscript tradition, which is partly due to the reproduction of the text by the Paris stationers' companies using the pecia system.
* The difference between the actual number of entries and the estimated number of quotations is due to Thomas' practice of combining multiple proverbs attributed to Seneca under a single entry. For example, the entry for Mors di comprises five short proverbs.