Does Human Nature Inherently Possess the Ten Dharma Realms?

The Tathāgatagarbha is fully endowed with the natures of the Ten Dharma Realms, whereas the manas (mental faculty) cannot possibly possess the complete natures of the Ten Dharma Realms. If the manas possessed Buddha-nature, then one would become a Buddha in a single thought-moment. If this were the case, if one expanded this single thought to ten, a hundred, or a thousand thought-moments, would it be possible to be a Buddha for half a day or a full day? The manas of a Buddha, or that of a Śrāvaka, Pratyekabuddha, or Bodhisattva, cannot possibly possess the evil natures of beings in the Three Evil Realms, nor do they possess the natures of ordinary beings within the Six Paths.

The fundamental nature refers to the mental factors (caitta). Observing the mental factors associated with the manas reveals a person's fundamental nature, while observing the mental factors of the Tathāgatagarbha provides even greater insight into the future destination of sentient beings, confirming beyond doubt that they will attain Buddhahood.

The manas of an ordinary being differs vastly from that of a Śrāvaka, Pratyekabuddha, or Bodhisattva, and also differs greatly from the manas of a Buddha. Furthermore, the mental factors associated with the manas and those of the Tathāgatagarbha also exhibit distinct differences. Only the manas of a Buddha and the mental factors of the Buddha's immaculate consciousness (amalavijñāna) are without any difference. If sentient beings were Buddhas in the true sense, then the mental factors of their manas should be identical to those of the Tathāgatagarbha: free from afflicted mental factors, fully endowed with the five universal mental factors, fully endowed with the five object-determining mental factors, and fully endowed with the eleven wholesome mental factors.