The pure mind in buddhism is not really about ethics. A pure mind refers to knowing things in an undistorted way. It is about vision. An impure mind refers to a distorted way of knowing. A pure mind refers to a non-distorted way of knowing. A pure mind sees things as they really are. This is beyond good and bad, merit and demerit.
The solution to suffering is to see all as it really is, not-distorted. Arising defilements tend to distort the mind which means; they distort the way we know things in the moment. The nature of mind is that it merely knows, it only reflects as it were, like a mirror. A mirror does not distort and is not engaged with reflections.
The pure mind or pure knowing likewise does not engage with what is seen, heard etc. Because it does not engage with like, dislike, indifference or 'this is me, this is mine, this is my self. …it is a bare awareness, a bare knowing, only knowing.
I believe, the nature of this mind, this pure mind, this bare awareness, is blissful, peaceful, cooled. It knows no stress, all feelings of loneliness, burden, unsatisfactory, they are absent.
The extinguishment of defilements results into a bare awareness, a pure mind, because everything that leads to engagement with what is seen, heard etc. is gone. When all that leads to engagement is gone (7 anusaya) there remains a bare awareness. This refers to a non-engaging, non-scattered, non-fragmented kind of knowing.
Because we do not know this is the real blissful nature of mind, an unburdened bare awareness without any engagement with the seen, heard, etc. we seek an escape for all the dukkha externally. We do not see nor understand that mind is not the problem but not knowing what mind really is, that is the problem! Not knowing the difference between a defiled and engaging mind and a not defiled non-engaging knowing. That avijja is what turns us into seekers externally.
I believe, pure mind as bare awareness, also has never been a stream of alternating sense moments. But this understanding of mind as a stream of alternating sense moments is merely how a defiled mind understands itself. A monkey mind that habitually grasps first this and then that what is sensed.
That monkey mind is lost some time in the visual domain, after that in the auditory domain etc. That mind knows itself as a stream of alternating sense moments. This does not mean, I believe, that this IS mind. This is how defiled, engaged mind functions. This is how defiled mind experiences itself.
The pure mind or the bare awareness does not function so fragmented and does not habitually become scattered over different sense domains. Only an engaging defiled mind does function so fragmented and scattered. That is its restlessness, its unease.
I believe it is impossible to arrive anywhere else then at this bare awareness. The oprooting of all defilements naturally cannot results in anything else then a bare awareness. But if one tries to see it, find it, search it, one cannot trace it. One cannot find it via engagement.
I believe bare awareness is not a sense vinnana nor an illusion that arises because of quickly alternating sense-moments. No, bare awareness is the natural result of a mind that does not engage. That has come to a halt. That does not drift alternatelety towards what is seen, heard etc. That is also its peace. That is uninclined, signless, empty, dispassionate, at ease, unburdened. A descent into emptiness (Mn121) is a descent into this bare awareness which is the base of stillness, the stilling of all formations, peace.