What does it mean to not think of dharmas and not think of dharma marks?

Original text of the Buddha Treasury Sūtra (Buddhapiṭaka Sūtra): 复次舍利弗。若有比丘教余比丘。比丘汝当分别观察诸法。亦复莫念法相。是比丘如是修习。心无系著。则能通达诸法一相。所谓无相。是人犹尚不生法相。况我人相。

Explanation: The Buddha said: Śāriputra, if there is a bhikṣu who can teach other bhikṣus, saying: Bhikṣu, you should skillfully differentiate and observe all dharmas, and while differentiating and observing all dharmas, do not fall into the appearances of all dharmas, do not define all dharmas as all dharmas, and do not dwell on the appearances and characteristics of all dharmas. If this bhikṣu cultivates in this way, his mind will be free from bondage, and he will be able to penetrate the single mark of all dharmas, which is the mark of no-mark. This person does not even give rise to the mark of dharmas, let alone the mark of self and the mark of a person.

Why is it said that one should observe all dharmas yet not dwell on the marks of dharmas? Because as long as one correctly and reasonably observes all dharmas, one will know that dharmas are not dharmas, that all dharmas are empty, all are without marks, and there are no dharmas with real substance. For example, when observing material form, one knows that material form is empty and illusory, without substance, that there is no real material form—that is, there is no mark of form. Therefore one should no longer cling to the mark of form, no longer define it as some material form, or grasp at its name and appearance. When observing sounds, smells, tastes, and tangibles, one should observe in the same way; correct and reasonable observation will reveal that these dharmas are fundamentally not sounds, smells, tastes, or tangibles, that they are all empty and illusory, without real substance. Then one should no longer cling to the dharma-marks of sounds, smells, tastes, tangibles, and mental objects, and no longer dwell on the dharma-marks of these dharmas.

After cultivating in this way continuously, the mind does not cling to dharmas or to dharma-marks; when there are no dharmas in the mind, it is empty, not bound by dharmas, and one attains the truth of the path, penetrating that all dharmas are empty and without marks. From then on, this person's mind does not even contain dharma-marks—how could there be the mark of self and the mark of a person? Because self and person are among the dharmas; if dharmas do not exist, self and person certainly cannot arise.

Original text: 舍利弗。于意云何。念法相者。是人能灭一切法不。不也。世尊。舍利弗。如树无根。能有枝叶华果实不。不也。世尊。

如是。舍利弗。若人不得诸法根本。是人能生诸法相不。不也。世尊。舍利弗。若人不得不念法相。是人能灭一切法不。不也。世尊。

Explanation: The Buddha said: Śāriputra, what do you think? Can a person who dwells on dharma-marks extinguish all dharmas? Śāriputra said: No, World-Honored One. The Buddha said: Śāriputra, for example, if a tree has no roots, can it produce branches, leaves, flowers, and fruit? Śāriputra said: No, World-Honored One.

The Buddha said: Therefore, Śāriputra, if a person cannot find the root and substance of dharmas, can this person give rise to the dharma-marks of dharmas in his mind? Śāriputra said: No, World-Honored One. The Buddha said: If a person cannot obtain the root and substance of dharmas, and does not dwell on the marks of dharmas, can this person extinguish all dharmas? Śāriputra said: No, World-Honored One.

This passage explains the principle that dharmas neither arise nor cease. Why do dharmas not arise? Because dharmas are rootless, without substance, empty and illusory, unobtainable. Why are dharmas not extinguished? Because dharmas are empty and fundamentally nonexistent; since they have no real existence, how could they be extinguished? Who could extinguish emptiness? Since dharmas are empty, who conjured them up? It is the tathāgatagarbha, the source of all dharmas, that conjured up all dharmas. Because dharmas are conjured, they are empty, unobtainable, neither arising nor ceasing. Arising is a false appearance, and ceasing is equally a false appearance—how could false appearances have arising and ceasing? This passage may sound perplexing and mind-bending, but after seeing the Way, one will suddenly understand it clearly.

Original text: 是人不得于法。不得法相。不得于灭。亦不分别无生无灭。是人尔时不生不灭。不名得涅槃者。亦复不名无得涅槃。舍利弗。如是教者名善知识。第一义中。无善知识。无恶知识。

Explanation: The Buddha said: This person has no dharmas in his mind, nor dharma-marks; he does not extinguish dharmas or dharma-marks, nor does he differentiate between the non-arising and non-ceasing of dharmas. At this time, this person's mind abides in non-arising and non-ceasing. Even so, one cannot say this person has attained nirvāṇa, yet one also cannot say this person has not attained nirvāṇa. Śāriputra, one who teaches in this way is a good spiritual friend (kalyāṇamitra). In ultimate truth (paramārtha), there is fundamentally no good spiritual friend and no bad spiritual friend.

One who recognizes the empty and false marks of all dharmas has no dharmas in his mind, and of course no appearances of dharmas either; he does not differentiate or cling to the existence or nonexistence of dharmas, his mind does not cling to the marks of arising and ceasing of dharmas, and having become quiescent, he realizes nirvāṇa. Because dharmas are empty, there is also no nirvāṇa-dharma or dharma-marks; therefore it is not called nirvāṇa, nor is it called non-nirvāṇa. By the same reasoning, in ultimate truth there are no dharmas, no good spiritual friends and no bad spiritual friends, nor any appearances of good or bad spiritual friends—all are empty.