This is from the book "Tranquillity's Secret" being published by me on Medium.com:
I have only run across this idea, framed from the perspective of one’s comportment towards the events of the world, in a fairly recent revival of the doctrine of “Unconcoctability” (in Pali: Atammayatā) today found in Theravada Buddhism. Part of the reason why it is absent from the more general spiritual conversation may be because of the conversational/teaching focus on the intellectual realizations, rather than the comportment changes that arise as a result of a prolonged and consistent meditation practice. But even in this revival of the doctrine, there remains only a vague understanding of what it actually consists in:
Regarding atammayatā, Santikaro Bhikkhu points out that even the
classical commentarial tradition, while recognizing the importance of
the term, interprets it quite vaguely, essentially connecting it with
the three basic constituents of mental proliferation, papañca.
Atammayatā appears in a number of Pali suttas and each context
suggests that the term has important meaning. The traditional
commentators, however, never caught on. They glossed atammayatā in a
way that suggested the term was out of their depths: they rendered it
as an absence of taṇhā (craving), absence of diṭṭhi (wrong views), and
an absence of māna (conceit).
In the Atammayasutta:
In seeing six rewards, it’s enough motivation for a monk to establish
the perception of not-self with regard to all phenomena without
exception. Which six? “I won’t be fashioned in connection with any
world. My I-making will be stopped. My my-making will be stopped. I’ll
be endowed with uncommon knowledge. I’ll become one who rightly sees
cause, along with causally-originated phenomena.” In seeing these six
rewards, it’s enough motivation for a monk to establish the perception
of not-self with regard to all phenomena without exception.
And completing the depiction:
In the commentary on the Atammayasutta Buddhaghosa states once more
that: the practitioner is not “made of that,” namely that he is devoid
of thirst, and—this time adds—wrong opinions: tammayā vuccanti
taṇhādiṭṭhiyo, tāhi rahito: “‘Made of this’ are said to be thirst and
[wrong] opinions. He is devoid of both.”
> The reference to the erroneous opinions explicitly occurs also in
verse 853ab of the Suttanipāta. It appears in the Aṭṭhakavagga, the
oldest section of the text and one of the oldest of the Canon, towards
the end of the ninth chapter, where we find the teachings that the
Buddha had given to Māgaṇḍiya. The topic of the chapter can be
summarized as follows: there is no need to embrace or reject a system
of thought. The one who compares himself with others embraces a system
and likes the discussions. The wise one does not compare himself with
others, because he gives up conceit (māna).
Does this Pali word, Atammayatā, truly mean what I wrote above in this dialog about realizations, insights, and enlightenment? Here is how Buddhadāsa Bhikkhu has explained it:
The word atammayatā is quite difficult to translate. We’ve spent a lot
of time thinking how to translate it into Thai, and then into English.
So far, the word that we feel is most correct as an English
translation is “unconcoctability,” or the inability to be concocted,
where there’s nothing that can concoct the mind. This is how we would
like to explain or translate atammayatā. If we take the word
atammayatā and break it up: a means ‘not’ or ‘un’; tam means ‘that’;
maya means ‘to fabricate, to make, or to concoct’; and then ta means
‘the state’. So it’s the state of not being concocted by that, meaning
not being concocted by anything. Atammayatā is when the mind is free.
The essence of atammayatā is the mind is completely free, so there’s
nothing that can concoct it, that can condition it. By the way, this
word ‘concoct’, if you’re not used to it, comes from the Latin word
‘to cook’. It means ‘to cook together’, and we use the word concoct to
mean the way the mind is brewed up, cooked up, conditioned, concocted
by things. When the mind is so free that nothing can touch it—nothing
can concoct it—we call that state, that realization, that
understanding atammayatā or ‘unconcoctability’. The essence of which,
the mind that is free of, has transcended everything, and so nothing
can affect it, nothing can concoct it.
The third and highest use of atammayatā is to signify the state of
mind that is totally free, independent, liberated. Tan Ajahn
Buddhadasa prefers to describe this state as being "above and beyond
positive or negative." Human beings instinctually feel and perceive
all experience as either positive or negative. This leads to
evaluating and judging those experiences, which turns into liking and
disliking those experiences, which in turn fosters craving,
attachment, and selfishness. Thus arises dukkha (misery, pain,
dissatisfaction). The mind that has gone beyond positive and negative
cannot be pulled into the conditioned arising (paticca-samuppada) of
dukkha. Thus, atammayatā in this, its most proper sense, describes the
state of the Arahant, the perfected, liberated human being.
The term atammayatā cannot be found in the Pali Text Society
Dictionary. Readers will find it difficult to discover references to
it in scholarly works, whether they come from West or East. The
meditation masters of Tibet, Burma, or Zen do not seem to be
interested in it. Mention it to most Buddhists and they will not know
what you are talking about. Yet there is clear evidence in the Pali
Canon that the Buddha gave this word significant meaning.
You are to know that this knowledge of atammayatā is very ancient but
it’s been forgotten. This knowledge used to exist, but then has been
 “Papañca is a pregnant and complex term that indicates the mental and emotional proliferation as a whole (conceptualizations, volitions, opinions, judgments, etc.) and that possesses three essential ingredients: 1) taṇhā, thirst or self-centered desire, 2) diṭṭhi, opinion or, more precisely in this context, uncritical belief or mental acceptance of something without verification, and thus erroneous opinion; 3) māna, conceit, which traditionally has nine aspects, which depend on whether the comparison is done with people who are believed to be inferior, equal or superior to oneself.”
-taken from: Atammayatā in the Pāli Nikāyas, by Francesco Sferra, Annali, Volume 67, Università Degli Studi Di Napoli “L’orientale”
 Francesco Sferra, Ibid.
 Aṅguttara Nikāya, Book of the Sixes, translated by Thanissaro Bhikkhu, 1998
(retrieved from: https://suttacentral.net/an6.104/en/thanissaro on 18-May-2020)
 Francesco Sferra, Ibid.
 Atammayatā by Buddhadāsa Bhikkhu,
Interpreted into English by Santikaro Bhikkhu,
A Dhamma lecture (1/5) given at Suan Mokkh on 5 February 1989
 Atammayata:The Rebirth of a Lost Word
By Santikaro Bhikku, Evolution/Liberation #4 (1993)
 Santikaro Bhikku, Ibid.
 Buddhadāsa Bhikkhu, Ibid.