This contribution gives a detailed analysis of the first Quaestio of the collection of grammatical quaestiones preserved in the MS Oxford, CCC 250, ff.30vb-33vb (§ § 1–3); an attempt is made to assign the Quaestio its proper place in the development of 12th-century linguistic thought (§ § 4–6). The subject matter of the Quaestio is the various interpretations of the infinitive used in a proposition as a noun (in vi nominis) as exemplified by “legere est agere”, a topic closely related to the discussions on the status of the dictum propositionis. The anonymous author deals with it from a logical point of view, and his main concern appears to be the truth of the proposition. The influence of contemporary views as the ‘contextual approach’ is shown by his proposal to judge the interpretation of the infinitive according to the syntactic structures of the propositions. His conditional interpretation of the proposition “legere est agere” in the sense of “si quis legit, agit” in the case of an ‘impersonal interpretation’ of the infinitives and the copula is judged worthy of our attention (§ 3). § 4 is devoted to discussions of this topic (and related questions) in 12th-century texts on logic. Special attention is paid to Abailard’s ‘impersonal interpretation’ of the infinitive in his theory on the ‘dictum propositionis’, and to the Ars Meliduna and the Dialectica Monacensis for the use of the term ‘attributum’. The minor textbooks of logic are considered to be the direct source of the example “legere est agere”. We find a comprehensive treatment of the question at issue in the Summa on the Priscianus minor by the Parisian Master Robertus (fi. ca.1160), but now from a grammatical point of view (§ 5). His main concern is the congruity of the construction. He admits both interpretations: in vi verbi and in vi nominis, but does not make any further sub-distinction of the use in vi nominis. Twice Robertus refers to an opinion adhered to by the author of our Quaestio, but rejected by Robertus himself. — An edition of the Quaestio is appended.