Five Ranks (of Ts'ao-tung) 

This is a classic statement of the nature of reality first formulated by the founder of the Ts'ao-tung school of Chinese Ch'an, Tung-shan Liang-chieh (807-69), and passed down through the Ts'ao-tung school to its Japanese successor, the Sōtō school as the central understanding of this line of Ch'an. Using a series of five verses composed by Tung-shan, it presents five different ways of viewing the nature of ultimate reality as it manifests in particular phenomena. (1) The Absolute is seen in the identity of all differentiated phenomena in so far as they all share in the ultimate nature of emptiness, (2) The Absolute is seen in each and every individual phenomenon considered separately, since the nature of all things is complete and sufficient in itself, (3) The Absolute contains within itself the potential to manifest all particular phenomena, even those that are opposite or contrary to one another, (4) Despite their identity in terms of their ultimate nature, all phenomena are distinct and unconfused. In fact, it is only in their real differentiation that their relationality to each other and to the Absolute can be seen—for example, both fire and ice arise from the Absolute and share the same fundamental nature, but fire is not ice and ice is not fire, (5) The enlightened mind directly perceives the active and dynamic interplay between the Absolute and individual phenomena, and between one phenomenon and another.

A Dictionary of Buddhism, Oxford University Press, 2003, 2004 (which is available in electronic version from answer.com)