All phenomena are of the nature of suchness.

In the Platform Sūtra, the Sixth Patriarch said: 一切诸法若无常者，即物物皆有自性，容受生死，而真常性有不遍之处。故吾说常者，正是佛说真无常义。

Self-nature gives rise to all dharmas, and the essence of all dharmas is also self-nature. Self-nature is permanent (constant), and since all dharmas are spoken of in dependence upon self-nature, they too are permanent. If all dharmas were impermanent, then all things would have their own self-nature (svabhāva), able to arise and cease by themselves; they would not be born from self-nature, nor would self-nature be needed to give birth to them, and then self-nature would have places it does not pervade. However, this is impossible; therefore, all dharmas, spoken of in dependence upon self-nature, all share the permanence of the suchness self-nature. If it were said that one dharma is impermanent, then that dharma would have its own self-nature, for only with a self-nature can there be talk of birth and death — then would not suchness have places it does not pervain, dharmas it cannot give birth to?

When all dharmas are spoken of in dependence upon the suchness self-nature, they are all of suchness nature, neither arising nor ceasing. Because these dharmas are all born of the suchness self-nature and all possess the nature of suchness, all dharmas are likewise permanently existent and imperishable. As long as there is the suchness self-nature, all dharmas will always appear. If all dharmas were impermanent, then once they ceased they could not arise again; if they could not arise, that would mean the suchness self-nature does not function and cannot produce dharmas — that would mean the suchness self-nature has places it does not pervade. However, this is impossible: the suchness self-nature pervades all places; everywhere and all dharmas are the suchness self-nature; wherever there are all dharmas, there is the suchness self-nature. Moreover, the seeds inherently present in suchness neither arise nor cease and endure forever; as long as they meet with conditions, they will give birth to all dharmas.

The meaning of what the Sixth Patriarch said is: if all dharmas were impermanent, then all things would each have their own self-nature, and these things could arise and cease by themselves, in ceaseless arising and ceasing; in that case they would not need the suchness self-nature to give birth to them, and self-nature would have places it does not pervade — this would contradict the meaning of the sūtras. Therefore, when the Sixth Patriarch said that all dharmas are permanent, this is precisely the true meaning of impermanence that the Buddha taught. That all dharmas are permanent shows that all dharmas are born of and manifested by self-nature; thus all dharmas have no self-nature of their own, and therefore they are impermanent.