無量壽經優婆提舍願生偈註 2.49

2.49

The reason these three kinds are spoken of together is that they are of the same class. Why is this said? First, the class of the six great elements, namely empty space, consciousness, earth, water, fire, and wind. Second, the class of non-discrimination, namely earth, water, fire, wind, and empty space. The reason only three classes are spoken of is that the single element of consciousness belongs to the realm of sentient beings; the single element of fire is absent there; and although there is wind, wind cannot be seen and has no abiding place. Therefore, from among the six elements and five classes, those three that exist and can be adorned are taken and spoken of together.