In some respects the Peruvian civilization was developed to such a degree as challenged admiration. The Peruvians were highly skilled in agriculture and in some kinds of manufactures. No people ever had a more efficient system of industry. This created their wealth and made possible their great public works. All accounts of the country at the time of the Conquest agree in the statement that they cultivated the soil in a very admirable way and with remarkable success, using aqueducts for irrigation, and employing guano as one of their most important fertilizers. Europeans learned from them the value of this fertilizer, and its name, _guano_, is Peruvian. The remains of their works show what they were as builders. Their skill in cutting stone and their wonderful masonry can be seen and admired by modern builders in what is left of their aqueducts, their roads, their temples, and their other great edifices. They had great proficiency in the arts of spinning, weaving, and dyeing. For their cloth they used cotton and the wool of four varieties of the llama, that of the vicuña being the finest. Some of their cloth had interwoven designs and ornaments very skillfully executed. Many of their fabrics had rare excellence in the eyes of the Spaniards. Garcilasso says, “The coverings of the beds were blankets and friezes of the wool of the vicuña, which is so fine and so much prized that, among other precious things from that land, they have been brought for the bed of Don Philip II.” Of their dyes, this account is given in the work of Rivero and Von Tschudi: “They possessed the secret of fixing the dye of all colors, flesh-color, yellow, gray, blue, green, black, etc., so firmly in the thread, or in the cloth already woven, that they never faded during the lapse of ages, even when exposed to the air or buried (in tombs) under ground. Only the cotton became slightly discolored, while the woolen fabrics preserved their primitive lustre. It is a circumstance worth remarking that chemical analyses made of pieces of cloth of all the different dyes prove that the Peruvians extracted all their colors from the vegetable and none from the mineral kingdom. In fact, the natives of the Peruvian mountains now use plants unknown to Europeans, producing from them bright and lasting colors.”