仁王經疏 3.156

3.156

Explanation: Second is cultivating the patience of impurity. This itself has three kinds: first, contemplating the impurity of the six great elements; second, contemplating the impurity of the faculties; third, contemplating the impurity of the three realms. Here, contemplating the six great elements means that the bodies of sentient beings are formed of the six elements, namely the four great elements as well as the space element. The defiled consciousness of the form realm is also entirely defiled and destructible, and hence is called impure. Contemplating the six elements separately is therefore called "part by part."