As you are likely aware, Vajrayana Buddhism is practiced by only about 6% of Buddhists
(as compared to 56% of Buddhists being Mahayana, and 38%Theravada).  My temple's main Buddhists
(Teachers) are rather esoteric in this way and the views do not reflect 90% plus of Buddhist practice.  Many of us
other Buddhists see the esoteric as unwarranted, poorly-founded, likely not effective shortcuts, PLUS as I indicate below
w/r to Dzogchen: they hold views in conflict with, and contrary to, Theravada Buddhism AND the historically recognized
actual words of the Buddha -- in particular the nearly completely unfounded views of our "luminous minds" and the unfounded
view of 'looking within' for good, i.e. Buddha-nature.
As I have shown, both "agreeable views" are not so, and this is substantiated by my research into the four major Nikayas
(all this data is presented in BOLD, below).
I am not proposing esoterics change or stop what they are doing at all, but it is likely not well-justified
to present esoteric Buddhism as modern Buddhism which is simply building on the Theravada foundation
(because: it makes little difference if you give a respectful nod to Theravada, but then contradict it).

(Again: You will find my actual research findings based on the words of the Buddha in BOLD, below):

First, I'll note (in partial summary/overview) that I have read two very large (recommended) books on Dzogchen
and do not find their main point of view, their idea of the 'luminous mind' we all supposedly have, supported by the
suttas or by the main commentaries. In fact, I find it false to the Buddha AND contrary. (Dzogchen may seem a likeable
idea in a couple of regards, like so much that is false and wrong.)

You can find ONE page from the Aguttara Nikaya where one could interpret 'luminous' as relating to ordinary minds:
(BUT, as one should know: any notable truth was repeated by the Buddha many times -- and in regard to 'luminous',
 what he repeated many times WAS THAT 'LUMINOUS' WAS A DESCRIPTION OF ENLIGHTENED MINDS.)
Anyhow, here is the quote from the ONE page that is subject to the interpretation the Dzogchen people
want to give it:  (see below for the many, many uses of luminous used ONLY to refer to the Enlightened):
"Luminous, monks, is the mind. And it is defiled by incoming defilements.".  Well, this
is basically the ONE AND only occurrence where the Buddha uses 'luminous mind' in a context
that may _seem_ to support the Dzogchen perspective.

Some months back, out of curiosity and in response to one teacher citing that
quote, I searched all the 4 main Theravadan Nikayas (Connected, Middle-Length, Long, and Numerical)
for the word 'luminous'.  Here is my complete findings:  You will see that on ALL other occasions
(except the one quoted just cited & a couple more on the same ONE PAGE), the
word comes up in the context of THOSE WHO ARE ENLIGHTENED
.  Here are the details:

The word 'luminous' comes up several times, looking at all the suttas in all the sources noted
(all major Theravada sources -- the 4 major Nikayas ).
[ AND, again, when  it comes up, it is all but that one time clearly used to refer to characteristics of an enlightened one
-- and comes up once in a different context, other than the 'mind', altogether) ]:
To wit:

Long Discourses: only 2 near-mentions:

"self-luminous" (re: those near enlightenment)
"all-luminous" (re: where consciousness is signless -- characteristic of enlightened)

Middle Length Discourses: 0 (zero) mentions

Connected Discourses: 6 mentions -- one in a clearly different context:

  "whatever forms exist here or beyond, And those of luminous beauty ..."
  "restrain him from this O' luminous one!"
  "luminous ones with taints destroyed"
  "Tathagata [(Buddha)] becomes more buoyant, malleable, wieldly, and luminous" (3 times in same sutta)
[NOTE: all other uses but the one out-of-context are regarding an enlightened one. ]

Numerical Discourses: (several times, including self-luminous)
   "Luminous, monks, is the mind. And it is defiled by incoming defilements." OR
   "Luminous, monks, is the mind, but it is defiled by adventious defilements." OR
   "Luminous, monks, is the mind, and it is freed from adventious defilements." (all three versions
     are in just a few lines (4 sentences), all on the same PAGE, in a row; yet this unclear and
     isolated instance is apparently the ONLY possible justification or the 'luminous mind' of Dzogchen in the suttas)

Other uses in the Numerical Discourses:
   "... luminous, pliant and properly concentrated for the destruction of taints" (several times)
       (and several similar uses regarding pure gold)
   "passing from here, self-luminous, they roam in Nandana"
   "mind-made, feeding on rapture, self-luminous, moving through the skies, ... they thus remain for a long time"
   "luminous, with taints destroyed"

If this were any kind of central idea as Dzogchen-ers imagine it, it would occur more and it would occur in
the contexts they would want, and it would occur in those contexts more than just a few times. (OR:
Some equivalent thing would be said by the Buddha and be prominent -- but there are no such things.)

Also on this matter:
Wikipedia says Theravada Buddhists justify the concept of bhavanga precisely FROM the mention
of 'luminous mind' by the Buddha.  So, bhavanga is what it means! And, that is no luminous
mind like the Dzogchen people have as a premise, otherwise the Abhidhamma would have
not said nearly nothing about it.
 
Regarding major Theravada commentaries:
Abhidhamma commentators understand the bhavanga as the stream of mind we have when we are not conscious
i.e., thinking, perceiving, or imagining (but present when dreaming).  The Abhidhamma says almost
absolutely nothing about the bhavanga beyond what I just said, except that the bhavanga
arrests (stops) when we do any conscious processing of any kind, no matter how simple.
The bhavanga according to Bodhi, who teaches the Abhidhamma embodies all your karmic tendencies,
so it is kind of like a disposition -- in modern terms.

Also, the Abhidhamma also indicates no particular proclivity toward wholesome mental states or wholesome
mental factors; and, the Universal (ethically variable) factors (present
in all consciousness) do not have any inherently positive quality.


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I provided the material (above and below) to you so you have in your arsenal (if you do not already) :
many of the facts and situations concerning Dzogchen -- showing it is not Buddhism.

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Again, I think this is important, because what the Buddha said is sometimes grossly mis-characterized.

Here is the information on the other major matter:

Buddha never said "for wisdom look within" NOR anything like that. [ I knew that
if he had, I would have noticed it, but I did some research for others. ]:

Thanks to pdf documents and modern search capabilities, it is quite possible to search
all the 4 major Nikayas for the word "within".    "Within" (outside of normal
non-metaphorical uses, like 'within his country'), is used in a much more limited sense when referring
to people (and what they should do, etc.) than some people indicate AND it is more often and
usually in regard to negative things !!!  (<-- And, otherwise usually with respect to 'self'-verifications. )

The following is an extremely good representation of all the uses (w/r to people) of the
word "within" in the 4 major Nikayas: (it is VERY close to thorough, if not thorough): (note the frequency of
'source of bad things' OR the after-the-fact verifying nature of sensing "within" -- those are the what the
Buddha propose we 'look within' FOR.  (SO: what is wise itself is NOT IN ANY big sense "within us")):
The findings within the Nikayas show several repetitions, as is usual, of several of these:

within self find confidence
within him craving
there has arising within me
... the factors within name-and-form which craving arises ...
ignorance is comprised within these states

taints do not flow within me
underlying tendency to conceit no longer occur within

with change ... despair arise within
yet the underlying tendency to personality lies within him
underlying tendency to adhere to rules and observances lies within him
underlying tendency to ill will lies within him
while he harbors sensual lust within
(similarly for aversion)
sensual craving lie deep within one in regard to sensual pleasures
ignorance and unknowing lie deep within one in regard to the six sense bases for contact

doubt within

when there is greed within you, do you know: 'there is greed within me' and when there is
no greed ... do you know: 'There is no greed within me'?
(similarly for hatred , delusion, a state connected with greed, a state connected with delusion ... mental fault)
 
harboring sensual lust within, he meditates, cogitates, ponders, ruminates
(similarly ill will, dullness and drowsiness, restlessness and remorse, doubt )
[and regarding doubt: he does not understand as it really is the escape from arisen doubt [ <-- indicating the typical
  overall (internal and external) observing experience of a follower; otherwise it is verification done "from within", when things are good. ]

ignorance is comprised within these states

when they see this quality within themselves, they resort to remote lodgings

though prepared externally , it has not been purified within

delight in sensual pleasure does not lie within him
(similarly for ill will, harming, lying, and personal existence)

anyone who has developed and cultivated mindfulness of the body has included within himself whatever wholesome states ... that partake of true knowledge

one should know how to define pleasure, and knowing that, one should pursue pleasure within oneself

who knows right here within himself the destruction of all suffering

the self within you knows, O person, whether it is true or false

craving for existence do not lie within one in regard to states of existence
(similarly w/r to cravings for other things when one has reached a good point)

dwell within the sangha

hearts may be calmed within

cannot be impeded by any enemy or adversary from within or without

within samsara
within the range of bait

withing himself a bliss that is blameless

within my domain

(end of evidence cited)

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Also:  the true and very central Buddhist idea of striving, investigating, to come to see things (in the THE WORLD;
absolute realities) as they really are : that is really the OPPOSITE of looking for or sensing what is 'inside' (esp.
since there is no self, none).



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These are reasons, most basically, why Dzogchen is not Buddhism -- and in fact is OFF the Path.
[ Dzogchen is even more dangerous, likely by far, than the mistaken belief that achieving
  states of concentration by themselves (or inherently) bring virtue and wisdom -- also bad.  Regarding this latter matter:
  fact is: Many old-time Buddhist leaders MADE SURE people were fully leading a virtuous life, before
  even starting them with meditation; Analayo in his extensive commentary on the Satipatthana notes the very necessary
  and central role the 8-fold Path has related to meditation. Finally, most good Buddhists did not even do the kind
  of meditation we do -- it was very largely a monastic practice.* (see footnote) ]

One of the things I like most about Buddhism is the idea that you simply BELIEVE NOTHING.  YET,
it would be ONLY by willfully just believing that I could accept Dzogchen; obviously I will not do that.
Though still flawed in all 3 major ways, I have abandoned the wrong grasp of rules and the belief that
external observances can lead to liberation (along with having abandoned some major doubt and
having abandoned much of false view of self).

 

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* FOOTNOTE: Quoting Mahasi Sayadaw in his Manual of Insight (published for the first time in English in 2016):
"The principal emphasis of this book is to explain precisely this point:
how those who take the vehicle of insight to enlightenment practice -- that is, how to
develop pure insight without a foundation of tranquility concentration."  (<-- i.e. traditional meditation)

In this Manual: This quote is surrounded by huge major sections on the 'momentary concentration' involved --
a concentration that when cultivated properly ITSELF develops tranquility, according to
that same author (who was leader, main questioner, at the 6th Buddhist Council, 1954).

He also states that states of absorption may also be achieved during repeated 'momentary concentrations'.