The two truths are non-dual. Reality is an integrated unity. Chih-i illustrates this by quoting the metaphor of the drunk man in the Mahāparinirvāṇa Sūtra who perceives the sun as “spinning around.” A sober man correctly perceives that there is only one sun, one reality, and that the spinning of the sun as perceived by the drunk man is caused by his deluded and drunken state. A deluded person thus has mistaken perceptions of the way things are, but an enlightened person perceives reality as it is and can see that the deluded person’s perceptions are a mistaken interpretation of reality.

Reality is best described as “one,” integrated, and interpenetrating, but as Chih-i points out,

if one becomes attached to this reality, words concerning reality become empty words. Since a mistaken verbal view arises, it is called “crude.”[T. 33, 705a24-25]

Even the verbal expression “one truth” must be understood as an ultimately inadequate expression of reality. If one is attached to the concept of “one truth,” it is necessary to go one step further and deny the possibility of adequate verbal expression. In Chih-i’s words, which presage the Ch’an / Zen proclamation to not rely on written words, one must “destroy [the notion of one truth] by saying ‘no truth’.”

The one truth is [actually] no [truth]; all truth is at rest. Each and every [truth] is [ultimately] inexpressible …
It is necessary to say “no truth” for the sake of those who have not fulfilled attainment, and in their attachments give rise to delusion. For those who have real attainment, there is [a positive truth]; for those [lost] in vain speculation, there is none. [T. 33, 705a28-29; b15-16]

Once again we find the tension in Chih-i’s philosophy between the strong assertion that reality and truth are ultimately beyond language and rational concepts, and the recognition of the undeniable need to express the Buddha Dharma, “truth,” and “reality” with words and concepts which are more valid than others. This is the task undertaken by Chih-i in his lectures and writings.

[T]he threefold truth concept, though it is not in itself discussed in detail by Chih-i, provides the hidden structure behind Chih-i’s philosophy. It is the content of Chih-i’s insight into the nature of reality. It pervades Chih-i’s lectures after his first seclusion on Mt. T’ien-t’ai, compiled as the [ Profound Meaning of the Lotus Sutra ] and [Great Concentration and Insight], and provides the key for understanding Chih-i’s interpretation of the Buddha Dharma.

The final, ultimate level is that of the “Perfect threefold truth”, or the understanding of the threefold truth by those of the Perfect Teaching. At this level one realizes that “it is not only the Middle Path which completely includes the Buddha-Dharma, but also the real and the mundane [truths]. This threefold truth is perfectly integrated; one in three and three in one” (705a5-7). The mundane truth contains all of reality, is all of reality, and all of reality contains the mundane truth. The same is true for the real truth and the Middle, for emptiness and conventional existence. These are all synonymous, integrated; one yet three and three yet one. All of reality is empty, is conventionally existent, is the Middle. All of reality is simultaneously empty of substantial Being yet conventionally existent. The one subtle threefold truth is “incomparable” and “absolute subtlety.” This is the ultimate expression of the subtlety of reality.

Chih-i’s interpretation of “Subtle” … discusses in detail the meaning and implications of the term “subtle” in thirty categories, but first he makes a distinction between relative subtlety and absolute subtlety. Relative subtlety refers to that which is subtle only in contrast to that which is crude. For example, the teachings of Mahāyāna in general are complete, great, and subtle in relative contrast to the incomplete, small, and crude Hinayāna teachings. Chih-i criticizes Fa-yün for using the term subtle only in the sense of a relative subtlety. Absolute subtlety, on the other hand, refers to that which is subtle in itself, and not merely in contrast to that which is crude. This is explained with reference to the Fourfold Teachings. In the Tripiṭaka Teaching, the Dharma is taught expediently in accordance with the capacity of the listener, and opposites (such as crude and subtle) are integrated by denying the worldly truth and comprehending the real truth. In the Shared Teaching, the emptiness doctrine is utilized to illuminate the fundamental identity of phenomena and reality. In the Distinct Teaching one “returns” to the conventional world, seeks the absolute as conventional reality which is identical with the real, and realizes that nirvāṇa is this world of saṃsāra. In the Perfect Teaching all of the extremes are integrated, and one realizes that there is nothing which is not the Buddha-dharma. As Chih-i says, “There is nothing which is relative, and nothing which is absolute” (T. 33, 697a7).

Once again we are dealing with something which cannot be adequately verbalized. Nevertheless, as Chih-i points out, since we must use words to describe it, the term “absolute” is the best we can do. The person who can attain insight into this “absoluteness” without recourse to words is like a horse which enters the stable just by catching a glimpse of a whip and does not need to be actually whipped to know where to go. Those of us who must have recourse to words are left with the task of dealing with Chih-i’s detailed verbal explanations and his discussion of the implications of “subtlety.”

Rather than define what “mind” means, Chih-i utilizes this section to provide a doctrinal basis for his teachings on contemplating the mind, or one’s thoughts. He quotes the Avataṃsaka Sūtra [Flower Garland] that “the mind, the Buddha, and sentient beings are not distinct” (T. 9, 47Sc29), and emphasizes the unity of the three. Chih-i does not use this verse to support a mind-only idealism. He proposes instead that the mind, or one’s thoughts, is the most accessible of the three dharmas, and thus should be the focus of one’s contemplation and meditation. Since the Buddha, objects, other sentient beings, and so forth, are all part of one reality, they are all included when one concentrates on one simple thought. This is illustrated with another quote from the Avataṃsaka Sūtra: “If one disports one’s mind in the dharmadhātu as if in space, then one will know the objective realm of all Buddhas” (T. 9, 409cl). Chih-i interprets this passage in terms of the threefold truth:

The dharmadhātu is the middle. Space is emptiness. The mind and Buddhas are conventional existence. The three together are the objective realm of all Buddhas. This means that if one contemplates [the thoughts of] one’s mind, one can become endowed with all Buddha-dharmas. [T. 33, 696a20-22]

Contemplation of the thoughts in one’s mind is the most readily available method of practice and can lead to the attainment of Buddhahood and enlightenment concerning the true nature of reality, which is simultaneously empty and conventionally existent.

[In discussing the Buddha], Chih-i … emphasizes the unity or integration of the Buddha-realm with all other aspects of reality. As Chih-i rhetorically asks:

How can there be any dharma distinct from the Buddha? [There cannot.] All of the hundred realms and thousand suchnesses are the objective realm of the Buddha. [T 33, 696a4-5]

In other words, the Buddha is not a separate and detached realm from that of our world of passionate illusions, but an integrated and involved part of it. The difference is that only a Buddha truly understands and perceives reality as it truly is. Understanding this vast reality requires a vast and penetrating wisdom. Both objective reality and the wisdom of the Buddha are thus “inconceivable”, beyond conceptual understanding. In short, the dharma of the Buddha is “subtle.”

Buddha-nature as the conditional causes of Buddhahood refers to the inherent potential and propensity for Buddhahood within all sentient beings which allows them to practice and build up the proper causes and conditions for attaining Buddhahood. In terms of the “three tracts” this corresponds to one’s inherent disposition , if not obstructed by sundry passions and delusions, to perform the deeds required to realize the wisdom of a Buddha.

Buddha-nature as the complete cause of Buddhahood refers to the inherent potential for wisdom in all sentient beings. In terms of the “three tracts” this corresponds to the illumination of wisdom, which destroys delusions and reveals the true nature of reality. Buddha-nature as the direct cause of Buddhahood refers to the fact that all beings are inherently endowed with “the reality of true thusness” in that they all participate in the true nature of reality. In terms of the “three tracts” this corresponds to the true nature of reality which is non-illusory and un-differentiated.

These three aspects, again, are not detached from each other but different aspects of one Buddha-nature and one reality. The Buddha-nature, the potential in each sentient being to attain Buddhahood, consists of the ability to practice, the prior presence of wisdom which only needs to be uncovered, and participation in true reality, which is simultaneously empty and conventionally existent.

The rest of the characteristics of the Buddha consist of various virtuous qualities such as the four Universal Vows, the perfection of the six pāramitā, and so forth. The Buddha’s “retribution” is actually the “reward” of perfect enlightenment and so forth for completing all practices and attaining Buddhahood.

Another way to classify dharmas, or reality, is in terms of “tentative” and “real”. The term “tentative” refers to the conventional realm of language, expedient means, and the worldly truth, while the term “real” refers to the way things truly are, reality itself, the supreme truth. According to Chih-i, Fa-yün classified the first five suchlikes aspects as being “tentative” and corresponding to ordinary people, while the next four suchlikes are “real” and correspond to the insight of the sages. For Chih-i, however, the “tentative” and “real” are inseparable and interdependent – ordinary people and sages alike partake in both the tentative and the real – and the distinction between them is merely one of expediency. This is illustrated by interpreting the ten dharma realms with the threefold truth pattern. First, all ten realms from hell to Buddhahood are part of the same dharmadhatu, which is united by the fundamental universal nature of emptiness. Second, these are ten distinct realms in which there are conventional, yet real, differences between ordinary people and sages. Third, these ten realms are identical with the universe, and all of reality is included in the ten realms. Since each of the ten dharma realms contains the ten suchlike characteristics, there are one hundred suchlike characteristics. Since the ten dharma realms are also interpenetrating, there are one hundred dharma realms and one thousand suchlike characteristics.

Chih-i expands on Hui-ssu’s classification of reality into the three categories of sentient beings, Buddha, and mind. He points out that reality is classified in various ways and numbers. For example, many texts describe reality in terms of its oneness. Some texts refer to reality in terms of the two categories of name and visible form. Others, … classify reality into three dharmas. These numerical listings could continue indefinitely, up to the infinite variety of phenomena. For the category of sentient beings, Chih-i borrows a section from the second chapter of the Lotus Sūtra (T. 9, 5cl 1-13) which he interprets as classifying reality into ten categories. These are the “Ten Suchlike Characteristics” which characterize all dharmas, which are defined by Chih-i as follows:

1. 1. “Suchlike appearance”: that which has its point of reference externally.
   2. “Suchlike nature”: that which has its point of reference internally.
   3. “Suchlike essence”: that which intrinsically belongs to one’s self.
   4. “Suchlike power”: the power to influence.
   5. “Suchlike activity”: that which constructs.
   6. “Suchlike causes”: repetitive causes.
   7. “Suchlike conditions”: auxiliary causes.
   8. “Suchlike results”: repetitive results.
   9. “Suchlike retributions”: retributive effects.
   10. “Suchlike beginning and end ultimately the same”: “beginning” refers to the first suchlike of appearances, “end” refers to the ninth suchlike of retribution, and “ultimately the same” means that they are integrated and share the same reality.

The fact that these phrases each have three characters makes it easy to interpret them in the threefold truth pattern. Chih-i claims that each of these phrases has “three readings” which follow the threefold truth pattern of emptiness, conventional existence, and the Middle Path. First, if one emphasizes the first character “suchness”, this refers to the emptiness of all things, since the suchness of all dharmas is their lack of substantial Being. Second, if one emphasizes the various characteristics such as the appearances, nature, essence, and so forth, this refers to the conventional existence of all dharmas. Third, if one emphasizes the second character of “likeness”, this refers to the “middleness” of all dharmas – that they are simultaneously empty yet conventionally existent.

Chih-i begins his detailed discussion of “dharma” by examining the classification of “dharma” into three categories: sentient beings, Buddha, and mind. These three dharmas, based on a verse in the Avataṃsaka Sūtra [Flower Garland Sūtra], are a classification of all reality into three subjective categories. “Mind” refers to the perceiver of objects (reserving for now the judgement as to the status – real, illusory, imaginary, or not – of these objects) and the subject which needs to be perfected in order to attain enlightenment. “Sentient beings” refers to the diversity of realms which the subject experiences, from that of hell to Buddhahood. “Buddha” refers to the subject perfected, the realm of enlightenment in which reality is correctly perceived. Thus these three dharmas are not separate and independent entities, but interpenetrating and integrated. All sentient beings have a mind which, depending on various causes and conditions, has the potential to experience any and all realms from hell to Buddhahood.