adversaria

Adversaria is a Latin term meaning things to be noted or opposed, and it has been used in scholarly contexts to refer to a miscellany of notes, observations, quotations, and references kept by a researcher. The word is the plural of adversarium, and in practice it denotes a working notebook rather than a finished treatise.

Historically, adversaria played a central role in classical and medieval scholarship. They were handheld collections where authors would jot down passages, marginalia, glosses, emendations, and snippets drawn from various authors. These notes functioned as aids for textual criticism, interpretation, and the preparation of commentaries or editions. Because the materials were often gathered without a fixed organizational scheme, adversaria could resemble a personal scrapbook of knowledge, organized more by topic or author than by a formal outline.

In the fields of botany and natural history, the term was also used for personal notebooks or compilations that recorded plant identifications, descriptions, and observations. Such adversaria served as reference repositories that researchers could later compare with other sources or published works.

In modern scholarship the term is mainly of historical interest. It is closely related to the concept of a commonplace book, marginalia, and scholia—forms of collected notes that supported later scholarly editing and interpretation. Today, adversaria are sometimes studied as historical evidence of scholarly practice and the workflows of early editors and naturalists.