Renunciation can be learned naturally. One must first train one's sense of discrimination, and discriminate between what is more valuable and what is less valuable. One can learn this by testing, as gold is put to the test by comparing it to imitation gold: that which lasts for a little time and then turns black is imitation, that which always keeps its color is real. This shows that the value of things can be recognized by their constancy. One might ask: should we not recognize the value of things by their beauty, but we must recognize beauty by its durability. Think of the difference in the price of a flower and a diamond. The flower with all its fineness, beauty of color and fragrance falls short in comparison with the diamond. The only reason is that the beauty of the flower will fade the next day, while that of the diamond will last.