Nephrite such as Lantian, Shaanxi, were also in great demand). There, white and greenish nephrite jade is found in small quarries and as pebbles and boulders in the rivers flowing from the Kuen-Lun mountain range northward into the Takla-Makan desert area. River jade collection was concentrated in the Yarkand, and the White Jade (Yurungkash) and Black Jade (Karakash) Rivers in Khotan. From the Kingdom of Khotan, on the southern leg of the Silk Road, yearly tribute payments consisting of the most precious white jade were made to the Chinese imperial court and there transformed into "objets d'art" by skilled artisans, as
Theory of forms to some of the problems that are made to puzzle the younger. The dialogue does present a very real difficulty with the Theory of Forms, which Plato most likely only viewed as problems for later thought. These criticisms were later emphasized by Aristotle in rejecting an independently existing world of Forms. It is worth noting that Aristotle was a pupil and then a junior colleague of Plato; it is entirely possible that the presentation of "Parmenides" "sets up" for Aristotle; that is, they agreed to disagree. One difficulty lies in the conceptualization of the "participation" of an object in a