Dedicated to the memory of Amanda Claridge (1949–2022), thesaurus sapientiae
Antiquitatum Thesaurus: a familiar and challenging title for those involved in antiquarianism, recalling a long tradition of works. But why precisely the word thesaurus?
The term is derived from the Greek thesauròs: its basic meaning (‘storage’, ‘warehouse’) later took on special meanings precisely in literary works.  Thesaurus is, in the field of linguistics, a lexicon, a dictionary, from the early modern age (Thesaurus Linguae Romanae et Britannicae, by Thomas Cooper, 1565; Trésor de la langue française by Jean Nicot, 1606) to the contemporary (Thesaurus Linguae Latinae, Thesaurus Linguae Graecae or the world’s most comprehensive: Historical Thesaurus of English, 2009, all now available online): in short, the sum total of all the attested terms of a given language. Originating evidently in the realm of printed works, the term has remained for online linguistic databases  and has entered the language of computer science, to indicate in essence a closed vocabulary of words.
But the antiquarian thesaurus is not a lexicon and depends on a different tradition. In the second half of the 13th century, Brunetto Latini (Florence 1220/1230–1293), Dante Alighieri’s teacher, wrote, in langue d'oïl, a treatise in three books entitled Li livres du Tresor, in which he intended to “bring together in a small place things of the greatest value” (fig. 1). Just as a lord amasses riches not only for pleasure but to increase his power, to shelter his state in peace and war, so the Livres are a receptacle that collects a store of knowledge.  They are a repository of knowledge, which takes the form of an orderly compilation of texts differing in chronology, language and content, rearranged to form what is one of the first encyclopedias in the vernacular. 
If, therefore, a linguistic thesaurus is a census of every term, a thesaurus of knowledge, from Brunetto Latini onward, designates a collection of vast and composite, but chosen and ordered, material, which, however, has in turn a claim to exhaustiveness: a complete reservoir of knowledge to draw on, to learn from, to remember. From antiquity through the Middle Ages and the modern age, that ordered space is also a mental space. Thesaurus is a metaphor for memory. The orator Quintilian called it a thesaurus eloquentiae: memory is Latini’s mental treasure: a space of inner knowledge. 
Antiquarian thesauri derive from this idea of Brunetto’s Livres: to collect material on antiquities, to create an organized body of knowledge to provide a summa of knowledge on a given subject, when needed.
Antiquarian thesauri appear as early as the 16th and 17th centuries, dealing mainly with numismatics and epigraphy, disciplines that already had a solid tradition since the 16th century, and which were evidently systematized before others. The work that constitutes a kind of ‘bridge’ between lexical and antiquarian thesauri is Hubert Goltzius’s Thesaurus rei antiquariae huberrimus, made up, the author says, of an infinite and very diverse amount of things. The Thesaurus is a lexicon of names, epithets, definitions of everything related to ancient civilization: gods, emperors, colonies, etc. It is a compendium, arranged by themes, of words taken not from literary sources but from inscriptions and coins, with the idea of composing a thesaurus totius antiquitatis. 
There are no illustrations in Goltzius’ work: they would appear in thesauri a few years later, mainly in works on numismatics. Among many, in Abraham Gorleus’s Thesaurus numismatum (1605) – referring mainly to his own collection, but modeled on Fulvio Orsini’s Familiae Romanae – or later in the century in Thesaurus numismatum, illustrating Charles Patin’s collection (1672). That the collection and the ‘treasure’ somehow overlap is testified by Lorenz Beger’s Thesaurus ex thesauro Palatino selectus (1685), a double thesaurus (fig. 2): the work, as in Patin, but also the Palatine Elector’s museum, whose richness, completeness, and absolute value are evidently intended to be emphasized.
Beger’s Thesaurus is enriched with gems; it is a chosen corpus, selected and ordered according to a coherent classification of material. Beger himself, a few years later, will publish the Thesaurus Brandenburgicus selectus, in which he illustrates, with commentary in dialogue form, the collection of the Elector of Brandenburg, antiquities that are much more varied: coins, gems, small bronzes, statues (fig. 3). Although not in the title, but only in the preliminary pages, the museum is in any case defined, once again, a thesaurus.  Compared to Latini, Goltzius, and Patin himself, then, Beger leads us to an illustrated, composite, explained, and ordered thesaurus, but one whose boundaries coincide with those of a museum, a collection. Antiquarian thesauri, however, are not merely illustrated catalogs of collections, as prestigious as they might be – they cross their boundaries and characteristics.
Comprehensive collections of antiquities of diverse provenance, in the history of antiquarianism of the modern age, have been put together from the 16th century onward – including those that did not come to print – but they have not always been called thesauri (that of Pirro Ligorio or the Museo Cartaceo of Cassiano dal Pozzo, for example). Perhaps the feature of selection and order, organic to the idea of thesaurus, can only be provided by prints, although sometimes-even books may have a different number of plates from copy to copy.
Such is the case with the Thesaurus hieroglyphicorum, a very rare collection of engravings, often varying in the number of plates, edited around 1610 by Hans Georg Herwart von Hohenburg, probably the earliest compilation of images of objects from ancient Egypt (or of what was believed to be Egyptian) (fig. 4).
The contents of this thesaurus are composite: they are hieroglyphs (but not only) taken from obelisks, statuettes, canopic jars, etc. of very diverse provenance (objects in private collections, monuments, prints, etc.), and the meaning of the collection is clear: to bring it all together in one ‘place’, to provide a comprehensive compendium. And this is an early example of something that will evolve over time and that corresponds to the fundamental idea of an antiquarian thesaurus.
Also de la Chausse’s Romanum Museum reflects the idea of a museum, because like the Museo Cartaceo it is a museum of museums: it brings together a fine selection of antiquities, substantially small in size, annotated and divided by theme and typology. They are drawn from the most important collections in Rome, pointedly indicated, and from a few drawings. But it is more than a museum. The full title is Romanum Museum, sive thesaurus eruditae antiquitatis: in an alternative space, in a ‘virtual museum’ an original and organized set of objects is collected.  A thesaurus selectus like Beger’s, enclosed not by the walls of a museum, but by the boundaries of the city of Rome.
To disproportionately enlarge the cultural boundaries of a thesaurus are the Thesaurus antiquitatum Romanarum (1694–1699) by Johann Georg Graevius and the Thesaurus Graecarum antiquitatum (1697–1701) by Jacob Gronovius, in 12 and 13 tomes respectively (figs. 5, 6). Supplements by Albertus Henricus Sallengre (1716–1719)  and Giovanni Poleni (1737)  followed. All these works were further republished between 1732 and 1737. Not only that, Graevius continued his work by devoting himself to medieval Italy, beginning to publish the Thesaurus antiquitatum et historiarum Italiae (1704–1725), later completed by Peter Burmann. 
These monumental thesauri are a collection of previously edited treatises on every aspect of ancient civilization and, with some differences between them, selected and arranged thematically. They are composed according to the perspective that was most familiar to their authors, namely the edition of texts, so they no longer deal with antiquities and their images: instead, the antiquitates are those of Marcus Terentius Varro, the ancient civilization, not monuments. Precedence is given to the books, reproduced in full and if necessary translated into Latin in order to reach as wide an audience as possible. Thus, the idea of a ‘paper museum’ is also surpassed in function of a comprehensive analysis of the ancient world, carried out through the texts of a community of scholars from the past and present, and from different geographical origins.
Graevius and Gronovius set a standard of rigor and comprehensiveness that will forever bind to the word thesaurus, surpassing any previous work: anyone who publishes a work with that title will be confronted with them. An example is Ludovico Antonio Muratori, author of a four-volume epigraphic collection entitled Novus Thesaurus veterum inscriptionum in praecipuis earumdem collectionibus hactenus praetermissarum (1739–1742). To put it in Michail Chatzidakis’ words:
The choice of the term thesaurus in the title, hitherto used only in the Thesauri of Gronovius and Graevius (who, however, did not deal specifically with epigraphy, but with all areas of ancient cultures), betrays its author’s ambitious intention of wanting to set new standards within the discipline of epigraphy;
[...] in the era of the systematization of antiquarian knowledge [...] in his attempt to surpass his predecessors by presenting as complete a collection of inscriptions as possible, [Muratori] aspired to compose an edition that followed the rules of philological textual criticism, as evidenced by his numerous interventions in the editions of his predecessors, aimed at improving their allegedly ‘corrupt’ texts. 
A flaw? Bernard de Montfaucon, in the preface to his L’Antiquité expliquée (1719, 10 volumes and 1724, 5 supplements) acknowledges that the two authors have brought together everything that a person would struggle to find in a lifetime. But then, once faced with those 36 volumes (including supplements), how can one not become demotivated? Moreover, the thesauri include works often with conflicting theses, so how to orient oneself?  Montfaucon's concerns are twofold: an excessive bulkiness of the volumes, and the lack of selection, criticism and, fundamentally, usability. This is why Montfaucon, himself an editor of texts, makes a different choice: he collects everything that can be illustrated by images, and thus leaves aside topics such as laws or geography (well represented in the thesauri), because they cannot be depicted. He also selects useful images, reorganizes them into an original classificatory scheme, and accompanies them with a critical text.
Montfaucon really does reduce a large amount of information into a space he defines and organizes. For what we have said so far, L’Antiquité expliquée is a thesaurus, perhaps the most thesaurus of the thesauri, but if a thesaurus is a repertory to draw on when needed, Montfaucon conceived his work instead as a real course of study (of two years), to be read from beginning to end. It is not a thesaurus and thus from its title marks even more clearly the distance from its predecessors.
Montfaucon is the ‘guide’ of the Antiquitatum Thesaurus project, which, however, in its title also evokes the great works of Graevius and Gronovius (and Beger before them). On the one hand, it encompasses the usability – guaranteed today by the digital form –, the centrality ascribed to images, so dear to the Benedictine abbot and, on the other, the idea of completeness and exhaustiveness of the sources, within cultural boundaries that are perhaps even broader than in the tradition (e.g., the attention given to the ‘peripheries’). Further, there is an awareness of the community of artists, scholars, collectors, and patrons that composed the history of antiquarian culture in the 17th and 18th centuries. In this synthesis, Antiquitatum Thesaurus creates a new repository of knowledge for the scholars of today and tomorrow.
 For the text, available in Italian, see: Brunetto Latini: Il tesoro di Brunetto Latino, maestro di Dante Alighieri, ed. by Julia Bolton Holloway, Florence 2021, pp. 80.
 Two examples: Paolo Divizia: Il «Tresor» di Brunetto Latini tra fonti e volgarizzamenti: il caso della «Formula vitae honestae», in: Culture, livelli di cultura e ambienti nel Medioevo occidentale, Atti del IX Convegno della Società Italiana di Filologia Romanza, Bologna, 5–8 ottobre 2009, ed. by Francesco Benozzo, Rome 2012, pp. 357–371; Maria Teresa Rachetta: Sulla sezione storica del Tresor: Brunetto Latini e l’Histoire ancienne jusqu’à César’, in: Medioevo Romanzo 42/2 (2018), pp. 284–311.
 Lina Bolzoni: La stanza della memoria, Turin 1995, pp. 245–253; Mary Carruthers: The book of memory. A study in Medieval culture, Cambridge 1990, pp. 33–35. Major works on mnemonics not surprisingly include a Thesaurus artificiosae memoriae by Cosma Rosselli (1579).
 Hubert Goltzius: Thesaurus rei antiquariae huberrimus, Antverpiae, ex officina Christophori Plantini, 1579. Quotes from the preface dedicated to the geographer Abraham Ortelius, which precedes p. 1. The adjective huberrimus in the title obviously plays off the author's name (it would be uberrimus in classical Latin).
 Lorenz Beger: Thesaurus Brandenburgicus selectus, Coloniae Marchicae, Typis electoralibus 1696–1701 (3 vols.); see the Dedicatio to Elector Frederick III and Praefatio to the reader, unnumbered pages in vol. 1. On the Thesaurus see: 300 Jahre “Thesaurus Brandenburgicus”: Archäologie, Antikensammlungen und antikisierende Residenzausstattungen im Barock, ed. by Henning Wrede, Max Kunze, Munich 2006.
 Michel-Ange de la Chausse: Romanum museum, sive Thesaurus eruditae antiquitatis, Romae, ex typographia Joannis Jacobi Komarek, 1690.
 Albertus Henricus Sallengre: Novus thesaurus antiquitatum Romanarum, Hagae-Comitum, apud Henricum du Sauzet, 1716–1719 (3 vols.).
 Giovanni Poleni: Utriusque thesauri antiquitatum Romanarum Graecarumque nova supplementa, Venetiis, typis Jo: Baptistae Pasquali, 1737 (5 vols.).
 Margaret Daly Davis: Thesaurus antiquitatum Romanarum Graecarumque. Autoren- und Sachregister der Thesauren-Corpora (Venedig 1732–1737), Fontes 4 (http://archiv.ub.uni-heidelberg.de/artdok/volltexte/2007/386).
 Michail Chatzidakis: L’eredità di Ciriaco d’Ancona. Il Novus thesaurus veterum inscriptionum di Ludovico Antonio Muratori e lo studio dell’epigrafia greca nel primo illuminismo, in: Arte e cultura fra classicismo e lumi. Omaggio a Winckelmann, ed. by Isabella C. R. Balestrieri, Laura Facchin, Milan 2018, pp. 267–280, quotes from p. 268 and p. 273.
 Bernard de Montfaucon: L’Antiquité expliquée et réprésentée en figures, Paris, chez Delaulne et al., 1719 (10 vols.), quotes from vol. I,1, pp. v–vi; Supplement au livre de l'antiquité expliquée et représentée en figures, Paris, chez la veuve Delaulne et al., 1724 (5 vols.). On L’Antiquité expliquée see now: L'antiquité expliquée et représentée en figures de Bernard de Montfaucon. Histoire d’un livre, ed. by Véronique Krings, Bordeaux 2021.