The survey moves from the analysis of a well-known passage of Aulus Gellius concerning the punishment for theft in ancient legal cultures (N.A. 11.18). The close inspection of the precisely ordered structure of Gellian text reveals some hitherto undetected aspects of Gellius’ working method, providing insight into the manner in which he managed his legal sources (particularly Sabinus’ works). This issue, of literary and cultural interest (the exegesis discloses a sort of ‘commentary’ on Sabinus’ works), is at the core of the present study and extends throughout its first part. The relationship between Gellius and the works of the Roman jurists, however, does not exhaust the interest of N.A. 11.18. The structural analysis of Gellius’ Chapter 18 will enable us, in fact, to read in a new light the discussion on Roman theft provided by Gaius’ Institutes (Gai 3.183 ff.). We devote the second part of this study to a short analysis of Gaian text as well, which can be extensively compared with N.A. 11.18. The contrast between the structures of the two texts will help us track down some common elements, providing us with evidence of a shared underlying pattern. This result makes a textual contribution to the never-ending debate on the ‘model’ of Gaius’ Institutes, on the one hand, and to the palingenesis of Sabinus’ Libri iuris civilis, on the other.