Seeing that the correct Ultimate Truth as substance is difficult to describe, Chih-I employs three analogies to single it out. With these analogies, four cases are illustrated that correspond to the Four Teachings. This indicates that the Ultimate Truth bears different definitions in each of the Four Teachings. …

The employment of the third analogy with gold further illustrates the Ultimate Truth that is contained within all beings. This is about the gold contained inside the yellow rock. A foolish man does not realize that the rock contains gold and mistakes the gold-rock as a rock. This refers to an ignorant man who, though being endowed with the Buddha nature as the Ultimate Truth, does not know how to cultivate this inherent nature. The appraiser is able to melt the rock and extracts the gold, but he only keeps its value. This is analogous with the Two Vehicles, who only eliminate defilements for themselves, but do not know how to benefit others. When the goldsmith gets the gold, he is able to utilize it to produce all kinds of jewelry. This analogizes the bodhisattva of the Separate Teaching, who can enter the view of the Provisional Existence in order to transform living beings. When the immortal gets the gold, he is able to make elixir, whereupon he attains physical freedom, transformation, and sovereignty. This analogizes the bodhisattva of the Perfect Teaching, who is able to identify the Absolute Truth with the facts, for he knows that phenomenal appearances embrace truth, whereupon they are not different. With such a view of an integrated reality, Chih-i stresses that this bodhisattva is able to attain enlightenment at the moment when he brings forth a resolve to the Bodhi-mind. His accomplishment of one single body contains immeasurable bodies, whereon he can universally respond to all beings.

In view of an integrated reality, according to Chih-i, whether it is an ignorant man or the bodhisattva of the Perfect Teaching, all of them represent the Ultimate Truth, inasmuch as they all possess gold. In view of differences of the facts, rock is different from gold, gold is different from golden jewelry, and jewelry is different from elixir. (Vol. 2, Page 411-412)