“The Aztecs did have some sort of writing, and, though we have not yet learned how to read it, we may solace ourselves with the hope that enlightenment may sometime come; but the people of the Andes did not even use hieroglyphics. Their sole documents were knotted strings. These strings, which they called _quipus_, were of course merely aids to memory—in the same way that a knot in a handkerchief enables a husband to remember the instructions his wife gives him when he sets out for the city, and which could not be written down in many pages.... Nevertheless, we have traditions in plenty.... Starting with the reasonable assumption that there must have been a very considerable past before the Spaniards appeared, we may construct various more or less plausible surmises, based on the Cyclopean architectural ruins which are distributed about the country. Marvelous works they are, though their form, and the carvings with which they are decorated, are less impressive than their mere size and weight.... It has been very generally thought that they were the handiwork of the prehistoric Piruas; yet, since the Piruas are prehistoric, it is not to be expected that much historic information concerning them is obtainable.... The ruins had been abandoned long before the Spaniards came and the Indians knew nothing of their origin.” “Still, it is indisputable,” he goes on to say, “that in Peru the grade of culture found in Mexico at the time of the conquest must have been reached and passed many ages earlier. In proof of this we have the fact that the Peruvians alone had succeeded in domesticating animals. Only the dog had been adapted to man’s service in other parts of America. Here the domestic llama, for instance, was derived from the wild huanacu and the alpaca from the vicuna. Many centuries would be required in order to bring about these results. Several varieties of maize were also produced under cultivation, and the Peruvian species of cotton plant is known to exist only as it appears under cultivation. Wild tubers were found in Peru from which the potato was educed. Now, it has been proven by experiment that wild potatoes require a very long time to put on a civilized complexion. It was in Peru that the potato, as _we_ know it, was first discovered. It was not cultivated north of Darien. Raleigh brought the first specimens to Ireland in 1568, but it was not until the end of the eighteenth century that they came into general use in Europe. The Peruvians practiced irrigation and manured their crops with guano.” And he continues: