From [the time of his enlightenment] under the bodhi tree till [the time of] his nirvāṇa, [the Buddha] preached (or turned) altogether four kinds of Dharma [wheels].

First, the good and pure dharma wheel, which begins with the discourse on one goodness, and ends with that on the four immaterial heavens. [Its aim] is to remove the impurities of the three [evil] paths. Hence, we call it pure.

Second, the expedient dharma wheel. This means that one achieves the two kinds of nirvāṇa by means of the constituents of enlightenment with outflows. It [thus] is called expedient device (fang-p’ien).

Third, the true and real dharma wheel. It is meant to destroy the falsehood of the three [vehicles] and thus establish the good (“beauty”) of “the One” [Vehicle]. Hence it is called true and real.

Fourth, the residueless (wu-yū/aśeṣa or anupādiśeṣa) dharma wheel. This refers to the discourse on the [dialectical] merging and returning [of the three Vehicles to the One] and thus to preach the mysterious and eternally abiding meaning. [Hence] it is called without residue.