Leonid Zhmud* The Menaechmi https://doi.org/10.1515/apeiron-2022-0101 Published online March 24, 2023 Abstract: In the mid-first century BC Geminus of Rhodes, a scientist and philosopher close to Posidonius, composed a comprehensive Theory of Mathematical Sciences, in the surviving fragments of which the numerous characters are referred to plainly by name, with some of them being namesakes of other, more well-known mathema- ticians and philosophers. This paper tries to set apart the namesakes of Geminus, of which there are four in his fragments: Theodorus, Hippias, Oenopides, and Menaechmus. Keywords: Greek mathematics, namesakes, methodology of mathematics, Geminus of Rhodes Belying its title, this article will not examine the famous play by Plautus, but the problem posed by namesakes in the history of ancient thought. Greek sources often mention writers, philosophers, and scientists only by their names, with the patro- nymic, origin, and field of activity either left out or not preserved, which makes it difficult for us to choose between the carriers of a certain name in each particular case. With the significant rise in written output during the Hellenistic age this grew to be seen as a problem by the Greeks themselves. Demetrius of Magnesia, a gram- marian and a librarian living in Rome in the mid-first century BC, compiled a special treatise On Poets and Authors of the Same Name, complete with a catalogue of their works. 1 In the majority of cases when the person in question is of some renown, the problem yields a more or less satisfactory answer, since we usually possess a great number of additional details making it possible to understand who was meant. But whenever a lesser-known author is the case, distinguishing him from his namesakes becomes very difficult. Thus, three Stoic philosophers are mentioned in Diogenes Laertius’ list of 20 Theodori (II, 103–104), about whom we know next to nothing. The problem is further aggravated by a certain penchant to allocate credit to the eminent at the expense of their minors for which Robert Merton, the founder of the sociology *Corresponding author: Leonid Zhmud, Institute for the History of Science, RAS, St. Petersburg, Russian Federation, E-mail: l.zhmud@spbu.ru. https://orcid.org/0000-0002-4873-6442 1 For preserved named fragments, see Mejer (1981). apeiron 2023; aop