Son of Buddha wrote:'For a long time has this mind been defiled by passion, aversion, & delusion.'From the defilement of the mind are beings defiled. From the purification of the mind are beings purified[/color].SN 22:100 the True self is the Pure unconditioned Mind..(Tathagatagarbha)the same exact thing is also said in the Mahaparinirvana sutra.
But the Tahagatagarbha is beyond unconditioned mind and thus cannot be tainted anyway. It is realised. It is not understood by conditioned mind.
Queen srimala sutra
"Lord, whoever does not doubt that the Tathagatagarbha is wrapped up in all the defilement-store, also does not doubt that the Dharmakaya of the Tathagata is liberated from all the defilement-store. When anyone's mind reaches the ultimate purport of the Tathagatagarbha, the Dharmakaya of the Tathagata and inconceivable realm of the Buddha.
the Tathagatagarbha is not tainted the term is used to show it is under the defilements not that it is defiled itself.
thats true the conditioned mind is the "I" that clings to the 5 aggreagates the "I" cannot realise enlightenement cause the "I" "me" is the defilement itself.
Gain certaintly that the nature of mind is birthless. None of the phenomena of appearance and existence in samsara and nirvana have any independent existence whatsoever; they are by nature empty. Therefore, there is certainty that the nature of mind is birthless.
Gampopa A String of Pearls
"Lord, samsara is based on the Tathagatagarbha. It was with reference to the Tathagatagarbha that the Lord pointed out and explained, '[It is] without limit in the past.' Since there is the Tathagatagarbha, there is reason for speaking of 'cyclical flow' (samasra). Lord, as to 'cyclical flow,' no sooner do the sense organs for perception pass away than it [the Tathagatagarbha] takes hold of sense organs for perception, and that is 'cyclical flow.' Lord, the two natures, 'passing away' and 'rebirth' are conventional terminology for the Tathagatagarbha. Lord, 'perished' and 'born' are conventional terminology for the world (loka). 'Perished' is the loss of the senses. 'Born' is the renewal of the senses. But, Lord, the Tathagatagarbha is not born, does not die, does not pass away to become reborn. The Tathagatagarbha excludes the realm with the characteristic of the constructed. The Tathagatagarbha is permanent, steadfast, eternal. Therefore the Tathagatagarbha is the support, the holder, the base of constructed [Buddha natures] that are nondiscrete, not dissociated, and knowing as liberated from the stores [of defilement]; and furthermore is the support, the holder, the base of external constructed natures that are discrete, dissociated, and knowing as not liberated.
peace and love