About the authencity of modern meditation methods I've been reading a few sources, books, essays and teachings that discuss the idea that the current orthodoxy of Theravada and its modern meditation methods show great differences with what the suttas tell us (especially the ones characterized as being part of the early doctrinal strata) about meditation, jhana and its importance in the buddhist soteriology (i.e. the path towards &quot;salvation&quot; from dukkha and the cycle of rebirth).
For instance, some investigations conclude that methods such as Vipassana are not &quot;methods&quot; in the suttas, but qualities to be developed (along with samatha) with the practice of Jhana. And so, all the foundations of modern vipassana meditation would come from later sources, and not from the Buddha himself. The same could be said about concepts such as kasina, access concentration, nimitta (as lights seen during meditation), etc.
How well accepted is this idea between bhikkhu/nis, scholars, and lay practitioners? And what consequences does this have for our practice? Should we look for methods of meditation that could go back to the ones described in the suttas, putting aside other sources, such as Abhidhamma or Visuddhimagga?
Just to be clear, I'm not necessarily saying that modern methods are wrong or that they contradict the path laid by the Buddha. I'm just asking if those methods are recognized as not authentic (if we define &quot;authenticity&quot; as the quality of something conforming in form and content with what the Buddha supposedly taught, if we have any way of knowing that with more or less degree of certainty), although useful, inside buddhist circles in general.
You're absolutely right.
Here, I quote from a Dhamma talk by Ajahn Chah entitled &quot;Unshakeable Peace&quot;.

Concerning this issue of samatha and vipassanā, the important thing is
to develop these states in our own hearts. Only when we genuinely
cultivate them ourselves will we know what they actually are.

He describes samatha and vipassana as states above, and not methods.

Meditation is like a single stick of wood. Insight (vipassanā) is one
end of the stick and serenity (samatha) the other. If we pick it up,
does only one end come up or do both? When anyone picks up a stick
both ends rise together. Which part then is vipassanā, and which is
samatha? Where does one end and the other begin? They are both the
mind.

He says above that it does not make sense to separate vipassana and samatha.

As the mind becomes peaceful, initially the peace will arise from the
serenity of samatha. We focus and unify the mind in states of
meditative peace (samādhi). However, if the peace and stillness of
samādhi fades away, suffering arises in its place. Why is that?
Because the peace afforded by samatha meditation alone is still based
on attachment. This attachment can then be a cause of suffering.
Serenity is not the end of the path. The Buddha saw from his own
experience that such peace of mind was not the ultimate. The causes
underlying the process of existence (bhava) had not yet been brought
to cessation (nirodha). The conditions for rebirth still existed. His
spiritual work had not yet attained perfection. Why? Because there was
still suffering. So based on that serenity of samatha he proceeded to
contemplate, investigate, and analyze the conditioned nature of
reality until he was free of all attachments, even the attachment to
serenity. Serenity is still part of the world of conditioned existence
and conventional reality. Clinging to this type of peace is clinging
to conventional reality, and as long as we cling, we will be mired in
existence and rebirth. Delighting in the peace of samatha still leads
to further existence and rebirth. Once the mind's restlessness and
agitation calms down, one clings to the resultant peace.

See above: The natural way is to start by calming the mind to experience meditative peace (samadhi) arising from  the state or quality of serenity (samatha). But then this does not free one from suffering. There is still clinging.
Then the Buddha's investigation proceeded to examining the working of the mind and how it relates to suffering. This then leads to the state or quality of vipassana.

So the Buddha examined the causes and conditions underlying existence
and rebirth. As long as he had not yet fully penetrated the matter and
understood the truth, he continued to probe deeper and deeper with a
peaceful mind, reflecting on how all things, peaceful or not, come
into existence. His investigation forged ahead until it was clear to
him that everything that comes into existence is like a lump of
red-hot iron. The five categories of a being's experience (khandhas)
are all a lump of red-hot iron. When a lump of iron is glowing
red-hot, is there anywhere it can be touched without getting burnt? Is
there anywhere at all that is cool? Try touching it on the top, the
sides, or underneath. Is there a single spot that can be found that's
cool? Impossible. This searing lump of iron is entirely red-hot. We
can't even attach to serenity. If we identify with that peace,
assuming that there is someone who is calm and serene, this reinforces
the sense that there is an independent self or soul. This sense of
self is part of conventional reality. Thinking, &quot;I'm peaceful&quot;, &quot;I'm
agitated&quot;, &quot;I'm good&quot;, &quot;I'm bad&quot;, &quot;I'm happy&quot;, or &quot;I'm unhappy&quot;, we
are caught in more existence and birth. It's more suffering. If our
happiness vanishes, then we're unhappy instead. When our sorrow
vanishes, then we're happy again. Caught in this endless cycle, we
revolve repeatedly through heaven and hell.
Before his enlightenment, the Buddha recognized this pattern in his
own heart. He knew that the conditions for existence and rebirth had
not yet ceased. His work was not yet finished. Focusing on life's
conditionality, he contemplated in accordance with nature: ''Due to
this cause there is birth, due to birth there is death, and all this
movement of coming and going.'' So the Buddha took up these themes for
contemplation in order to understand the truth about the five
khandhas. Everything mental and physical, everything conceived and
thought about, without exception, is conditioned. Once he knew this,
he taught us to set it down. Once he knew this, he taught to abandon
it all. He encouraged others to understand in accordance with this
truth. If we don't, we'll suffer. We won't be able to let go of these
things. However, once we do see the truth of the matter, we'll
recognize how these things delude us. As the Buddha taught, ''The mind
has no substance, it's not any thing.''
The mind isn't born belonging to anyone. It doesn't die as anyone's.
This mind is free, brilliantly radiant, and unentangled with any
problems or issues. The reason problems arise is because the mind is
deluded by conditioned things, deluded by this misperception of self.
So the Buddha taught to observe this mind. In the beginning what is
there? There is truly nothing there. It doesn't arise with conditioned
things, and it doesn't die with them. When the mind encounters
something good, it doesn't change to become good. When the mind
encounters something bad, it doesn't become bad as well. That's how it
is when there is clear insight into one's nature. There is
understanding that this is essentially a substanceless state of
affairs.
The Buddha's insight saw it all as impermanent, unsatisfactory and
not-self. He wants us to fully comprehend in the same way. The knowing
then knows in accordance with truth. When it knows happiness or
sorrow, it remains unmoved. The emotion of happiness is a form of
birth. The tendency to become sad is a form of death. When there's
death there is birth, and what is born has to die. That which arises
and passes away is caught in this unremitting cycle of becoming. Once
the meditator's mind comes to this state of understanding, no doubt
remains about whether there is further becoming and rebirth. There's
no need to ask anyone else.
The Buddha comprehensively investigated conditioned phenomena and so
was able to let it all go. The five khandhas were let go of, and the
knowing carried on merely as an impartial observer of the process. If
he experienced something positive, he didn't become positive along
with it. He simply observed and remained aware. If he experienced
something negative, he didn't become negative. And why was that?
Because his mind had been cut free from such causes and conditions.
He'd penetrated the Truth. The conditions leading to rebirth no longer
existed. This is the knowing that is certain and reliable. This is a
mind that is truly at peace. This is what is not born, doesn't age,
doesn't get sick, and doesn't die. This is neither cause nor effect,
nor dependent on cause and effect. It is independent of the process of
causal conditioning. The causes then cease with no conditioning
remaining. This mind is above and beyond birth and death, above and
beyond happiness and sorrow, above and beyond both good and evil. What
can you say? It's beyond the limitations of language to describe it.
All supporting conditions have ceased and any attempt to describe it
will merely lead to attachment. The words used then become the theory
of the mind.
Theoretical descriptions of the mind and its workings are accurate,
but the Buddha realized that this type of knowledge was relatively
useless. We understand something intellectually and then believe it,
but it's of no real benefit. It doesn't lead to peace of mind. The
knowing of the Buddha leads to letting go. It results in abandoning
and renunciation. Because it's precisely this mind that leads us to
get involved with both what's right and what's wrong. If we're smart
we get involved with those things that are right. If we're stupid we
get involved with those things that are wrong. Such a mind is the
world, and the Blessed One took the things of this world to examine
this very world. Having come to know the world as it actually was, he
was then known as the ''One who clearly comprehends the world''.

Furthermore, without attainment of serenity, the five hindrances would obstruct any attainment of insight. So below, he teaches to calm the mind first.

Allow the breathing to flow easily at just the right pace, neither
too short nor too long. Don't try to make it into anything special.
Let the body relax, comfortable and at ease. Then keep doing it. Your
mind will ask you, ''How late are we going to meditate tonight? What
time are we going to quit?'' It incessantly nags, so you have to
bellow out a reprimand, ''Listen buddy, just leave me alone.'' This
busybody questioner needs to be regularly subdued, because it's
nothing other than defilement coming to annoy you. Don't pay it any
mind whatsoever. You have to be tough with it. ''Whether I call it
quits early or have a late night, it's none of your damn business! If
I want to sit all night, it doesn't make any difference to anyone, so
why do you come and stick your nose into my meditation?'' You have to
cut the nosy fellow off like that. You can then carry on meditating
for as long as you wish, according to what feels right.
As you allow the mind to relax and be at ease, it becomes peaceful.
Experiencing this, you'll recognize and appreciate the power of
clinging. When you can sit on and on, for a very long time, going past
midnight, comfortable and relaxed, you'll know you're getting the hang
of meditation. You'll understand how attachment and clinging really do
defile the mind.
When some people sit down to meditate they light a stick of incense in
front of them and vow, ''I won't get up until this stick of incense
has burned down.'' Then they sit. After what seems like an hour they
open their eyes and realize only five minutes have gone by. They stare
at the incense, disappointed at how exceedingly long the stick still
is. They close their eyes again and continue. Soon their eyes are open
once more to check that stick of incense. These people don't get
anywhere in meditation. Don't do it like that. Just sitting and
dreaming about that stick of incense, ''I wonder if it's almost
finished burning,'' the meditation gets nowhere. Don't give importance
to such things. The mind doesn't have to do anything special.
If we are going to undertake the task of developing the mind in
meditation, don't let the defilement of craving know the ground rules
or the goal. ''How will you meditate, Venerable?'', it inquires. ''How
much will you do? How late are you thinking of going?'' Craving keeps
pestering until we submit to an agreement. Once we declare we're going
to sit until midnight, it immediately begins to hassle us. Before even
an hour has passed we're feeling so restless and impatient that we
can't continue. Then more hindrances attack as we berate ourselves,
''Hopeless! What, is sitting going to kill you? You said you were
going to make your mind unshakeable in samādhi, but it's still
unreliable and all over the place. You made a vow and you didn't keep
it.'' Thoughts of self-depreciation and dejection assail our minds,
and we sink into self-hatred. There's no one else to blame or get
angry at, and that makes it all the worse. Once we make a vow we have
to keep it. We either fulfill it or die in the process. If we do vow
to sit for a certain length of time, then we shouldn't break that vow
and stop. In the meantime however, just gradually practise and
develop. There's no need for making dramatic vows. Try to steadily and
persistently train the mind. Occasionally, the meditation will be
peaceful, and all the aches and discomfort in the body will vanish.
The pain in the ankles and knees will cease by itself.