In war their skill was defensive rather than offensive. They built salients and re-entrant angles in their walls, and dry moats are often encountered. They domesticated the South American camel (the _llama_), which enabled them to carry out engineering and agricultural works far more difficult than they could have accomplished had they been obliged to depend on human bearers. In addition to maize, potatoes, and cassava, they had many other important crops, such as pineapples, peanuts, and cotton. Great is the treasure of precious and base metals which has come, and is to come, from Peru. But that sinks into insignificance beside the value of one corn and potato crop throughout the world. And in the future it seems not at all unlikely that the Incas, famous for centuries for their system of government, their masonry, and the treasures which the Spaniards took from them, will be yet more famous for the extent to which they developed agriculture. [Illustration: RUINS OF TORONTOY The man is seated on a carved rock, probably an altar] [Illustration: INCA IMPLEMENTS] * * * * * We can do no better, in closing this account of the old Peruvian empire, than to quote from Mr. Prescott’s imperishable work, “The Conquest of Peru,” the following summary of the characteristics of Inca culture: “Under the rule of the Incas, the meanest of the people enjoyed a far greater degree of personal comfort than was possessed by similar classes in other nations on the American continent--greater probably, than in feudal Europe. Under their scepter, the higher order of the state had made advances in many of the arts that belong to a cultivated community. By the well-sustained policy of the Incas, the rude tribes of the forest were gradually gathered within the folds of civilization, and of these materials was constructed a flourishing and populous empire, such as was to be found in no other part of America.” [Illustration: INCA POTTERY AND INSTRUMENTS] _SUPPLEMENTARY READING_ EARLY MAN IN SOUTH AMERICA _By Ales Hrlicka_ Bureau of American Ethnology, Bulletin 52 HISTORY OF THE CONQUEST OF PERU _By W. H. Prescott_ THE INCAS OF PERU _By Sir Clements R. Markham_ SOUTH AMERICAN ARCHEOLOGY _By Thomas A. Joyce_ STAIRCASE FARMS OF THE ANCIENTS _By O. F. Cook_ National Geographic Magazine, Volume 29, No. 5 FURTHER EXPLORATIONS IN THE LAND OF THE INCAS _By Dr. Hiram Bingham_ National Geographic Magazine, Volume 29, No. 5 THE STORY OF MACHU PICCHU _By Dr. Hiram Bingham_ National Geographic Magazine, Volume 27, No. 2 THE OPEN LETTER [Illustration: MONOLITHIC GATEWAY AT TIAHUANACO]