[40] Clavigero, Stor. del Messico, tom. i. lib. 2.--Torquemada, Monarch. Ind., tom. i. lib. 2.--Boturini, Idea, p. 146.--Col. of Mendoza, Part 1, and Codex Telleriano-Remensis, apud Antiq. of Mexico, vols. i., vi.--Machiavelli has noticed it as one great cause of the military successes of the Romans, “that they associated themselves, in their wars, with other states, as the principal,” and expresses his astonishment that a similar policy should not have been adopted by ambitious republics in later times. (See his Discorsi sopra T. Livio, lib. 2, cap. 4, apud Opere (Geneva, 1798).) This, as we have seen above, was the very course pursued by the Mexicans. [41] Ixtlilxochitl, Hist. Chich., MS., cap. 36. [42] [Robertson, in his History of America, was the first man to question the correctness of the judgment passed by the Spanish chroniclers upon the Aztec institutions. Subsequent American writers gave louder expression to his doubts. As has been said in the notes upon the preceding chapter, Mr. Morgan proved conclusively that the so-called “empire” was no empire at all, but only a confederacy of three tribes. Mr. Morgan, however, was sometimes led into inaccuracy and extravagance of statement because of his desire to place all the American aborigines on the same institutional plane. Adolf Bandelier, pupil and disciple of Morgan, persevering and accurate scholar, investigated the subject in an entirely unprejudiced way and with a thoroughness which forces men to place almost implicit confidence in his conclusions. It is well here to summarize those conclusions. The Mexican confederacy was made up of three tribes, the Aztecs, the Tezcucans, and the Tlacopans, who dwelt in neighboring pueblos.