The Spanish statements of facts are, of course, not to be accepted uncritically. When we are told of cut slabs of porphyry inlaid in the walls of a room, we have a right to inquire how so hard a stone could be cut with flint or copper chisels,[143] and are ready to entertain the suggestion that some other stone might easily have been mistaken for porphyry. Such a critical inquiry is eminently profitable, and none the less so when it brings us to the conclusion that the Aztecs did succeed in cutting porphyry. Again, when we read about Indian armies of 200,000 men, pertinent questions arise as to the commissariat, and we are led to reflect that there is nothing about which old soldiers spin such unconscionable yarns as about the size of the armies they have thrashed. In a fairy tale, of course, such suggestions are impertinent; things can go on anyhow. In real life it is different. The trouble with most historians of the conquest of Mexico has been that they have made it like a fairy tale, and the trouble with Mr. Morgan was that, in a wholesome and much-needed spirit of reaction, he was too much inclined to dismiss the whole story as such. He forgot the first of his pair of rules, and applied the second to everything alike. He felt "at full liberty to reject" the testimony of the discoverers as to what they saw and tasted, and to "commence anew," reasoning from "what is known of Indian society." And here Mr. Morgan's mind was so full of the kind of Indian society which he knew more minutely and profoundly than any other man, that he was apt to forget that there could be any other kind. He overlooked his own distinction between the lower and middle periods of barbarism in his attempt to ignore or minimize the points of difference between Aztecs and Iroquois.[144] In this way he did injustice to his own brilliant and useful classification of stages of culture, and in particular to the middle period of barbarism, the significance of which he was the first to detect, but failed to realize fully because his attention had been so intensely concentrated upon the lower period. [Footnote 143: For an excellent account of ancient Mexican knives and chisels, see Dr. Valentini's paper on "Semi-Lunar and Crescent-Shaped Tools," in _Proceedings of Amer. Antiq. Soc._, New Series, vol. iii. pp. 449-474. Compare the very interesting Spanish observations on copper hatchets and flint chisels in Clavigero, _Historia antigua_, tom. i. p. 242; Mendieta, _Historia ecclesiastica indiana_, tom. iv. cap. xii.]