The two passages have often been compared, but with no agreed result. For instance, H. Last, CQ XVII, 1923, 153 f., and K. Btichner, Lateinische Literatur und Sprache, Bern, 1951, 81 f., give the priority to the invectiva; A. Klotz, Berl. philologische Wochenschrift, XLIII, 1923, 261 f., and O. Seel, Klio, Beiheft XLVII, 1943, 73 ff., to the epistula; R. v. Pöhlmann, Sitzungsb. der K. Bayer. Akad., 1904, 27, and G. Carlsson, Eine Denkschrift an Cäsar über den Staat, Lund, 1936, 57, think that the passages may have a common source; B. Edmar, Studien zu den Epistulae ad Caesarem senem, Lund, 1931, 105 f. leaves the solution open. Progress can hardly be made without fresh evidence.