The first and most fundamental, “contemplating the realm of the inconceivable” (kuan pu-k’o-ssu-i Ching, kanfukashigi kyō), is to discern that the present object of contemplation is identical with the true aspect of reality, that is, the threefold truth. This is the portion of the text that sets forth the “single thought-moment comprising three thousand realms.” Since explanations of this concept in English sources are few, and since it is important not only in the medieval Tendai context but to the discussion in chapter 6 of Nichiren’s thought, it is worth presenting here in some detail.

The “single thought-moment” indicates the briefest possible instant in the thoughts of ordinary worldings that arise from one moment to the next, while the “three thousand realms” indicates the whole of phenomenal reality. In explaining the structure of “one mind” being “three thousand realms,” Chih-i says:

“Now one mind comprises ten dharma realms, but each dharma realm also comprises ten dharma realms, giving a hundred dharma realms. One realm comprises thirty kinds of realms, hence a hundred dharma realms comprise three thousand kinds of realms. These three thousand are contained in a fleeting moment of thought. Where there is no mind, that is the end of the matter; but if mind comes into being to the slightest degree whatsoever, it immediately contains the three thousand.”

Although each “thought-moment” is here said to “contain” the three thousand realms, Chih-i is careful to make clear that, in his system, the mind is not prior to dharmas:

“One may say neither that the one mind is prior and all dharmas posterior nor that all dharmas are prior and the one mind posterior. … If one derives all dharmas from the one mind, this is a vertical relationship. If the mind all at once contains all dharmas, this is a horizontal relationship. Neither vertical nor horizontal will do. All one can say is that the mind is all dharmas, and all dharmas are the mind. Therefore, the relationship is neither vertical nor horizontal, neither the same nor different. It is obscure, subtle and profound in the extreme. Knowledge cannot know it, nor can words speak it. Herein lies the reason for its being called ‘the realm of the inconceivable.’ ace;” (Page 178-179)