In an article published in 2003, Klaus Jacobi—using texts partially edited in De Rijk's Logica Modernorum—demonstrated that twelfth-century logic contains a tradition of reflecting about some of the transcendental names (nomina transcendentia). In addition to reinforcing Jacobi's thesis with other texts, this contribution aims to demonstrate two points: 1) That twelfth-century logical reflection about transcendental terms has its origin in the logica vetus, and especially in a passage from Porphyry Isagoge and in Boethius's commentary on it. In spite of the loss of the major part of the Aristotelian corpus, the twelfth-century masters in logic still received some Aristotelian theses concerning the notions of one and being via Porphyry and Boethius; on the basis of such theses, they were able to elaborate a sort of proto-theory of the transcendentals as trans-categorical terms. 2) That this theory is centred on the idea that there exists a particular group of names which have the property that they can be said of everything; this group includes "being", "one", "thing" and "something" (ens, unum, res, aliquid). Twelfth-century masters in logic try to question the (originally Aristotelian) thesis that these terms are equivocal, although they do not deny it completely.