My aim here is to present an editio princeps of a newly discovered Arabic translation of a very important passage from Plato's Republic (Book VI, 506d3–509b10) found in the work entitled Kitāb fī Masā'il al-umūr al-ilāhiyya (hereafter Masā'il), penned by the somewhat obscure Neoplatonist Abū Hāmid al-Isfizārī (fl. mid-fourth / tenth c.). While an edition of al-Isfizārī's work has been published by Daniel Gimaret, the manuscript he used (Ragıp Paşa 1463) lacked the literal translation of the Republic passage. The one other known exemplar of the work, MS Zāhiriyya 4871, dated slightly later than the first, appears to be closer to the author's original unedited version; it contains the Republic passage. I am currently preparing a new edition of the work on the basis of the Zāhiriyya manuscript, but it seemed worthwhile to bring the Republic passage to immediate attention. I do not attempt here a thorough evaluation of al-Isfizārī's philosophy as presented in the Masā'il; this can be done successfully only upon completion of the edition. However, to place the work in its proper context, I do provide a brief overview of the transmission of Plato's Republic in Arabic; a discussion of new information on al-Isfizārī's Nachlass, and a description of the two exemplars of his Masā'il. The edited text of the passage from the Republic is accompanied by a provisional translation.