user4821: I mean I don't know if they do but apparently private buddhas don't put forth a teaching, so my question is why can't they just tell people what they did to attain enlightenment.

user5676: If I remember well, in the gelugpa school of Tibetan Buddhism, private buddhas are synonymous with "small arhats", that have attained the "small nirvana", if they renounce it, they can go on and remove the first veil, at which time they become "aryas", and then the three others, at which time they become buddhas, alias fully awakened, alias "great arhats". 
Somehow private buddhas blocked their sufferings without removing the causes, and their state is an intermediary stage for those who want to reach buddhahood for the benefits of others and themselves.

user4742: One difference between a Sammasambuddha and Paccekkabuddha is that, the former, at a point of been capable of achieving Enlightenment, postpones his Enlightenment so that he can become a Bodhisattva to instruct and inspire many beings during many life times, and thus help a large number of beings eradicate craving (the origin of suffering). Thus over the supposedly billions of lifetimes as a Bodhisatva the Bodhisatva gets to know and learns about the various tendencies of the multitude of beings  s/he instructs, and thus is able to preach the dhamma accordingly. The latter had no such intention, and no such training in teaching. That is not to say that Paccekabuddhas are incapable of giving any instruction or inspiring others. However, the body of teaching is not comprehensive or complete like a Sammasambuddha. 

user3551: Also forgive me,I forgot where I read this but a pacekabuddha lacks the ability to teach like a supreme Buddha.Even the Buddha after his enlightened almost didn't teach the dhamma because he said it was too hard for us to understand.so I imagine it would have been much more difficult for a private Buddha to teach the dhamma.Especially when its never been heard before or not in a Buddha sasana.

user295: There is another view on why private Buddha's cannot teach.

A disciple understands the fabrication pertaining to ones own aggregates
A private Buddha understand above plus fabrication of nature but not that of other beings (some private Buddhas realise Buddhahood through observing nature than oneself)
A fully enlightened Buddha also understands the fabrication pertaining to the aggregates of others also, hence is able to provide and set out proper guidance a tame others who are ready to be tamed.

If you do not understand how fabrication work pertaining to another being you cannot give advice on how to come out of the process of creating new fabrications and put a stop to it.
There are documented cases in what they did to realise Nirvana but many are not readily usable by any one who is not mature enough. E.g. looking at a leaf fall fall from a tree, looking at the flow of a stream, etc. It is unlikely anybody else utilise this kind of advice to gain benifit.

user43: They do know. They're just not comfortable with teaching.
In Chapter III, karika 94c of Abhidharmakosabhasya, Vasubandhu explains that Pratyekabuddhas do not teach others because teaching Dharma requires pushing the students "against the current" to "make them understand the profound Dharma", which "is a difficult thing" and causes "turmoil" to Pratyekabuddha, who finds pleasure in the peace of Jhanas and is averse to human contact with its trouble:

Why does he not apply himself to the conversion of others? He is certainly capable of teaching the Dharma: he possesses the comprehensions, he can remember the teachings of the ancient Buddhas. He is no longer deprived of compassion, for he manifests his supernormal power with a view to being of service to beings.  He can no longer say that beings are "unconvertible" in the period in which he
  lives, for, in this period—the period of decrease of life—beings can detach themselves from The Realm of Desire by the worldly path. Why then does he not teach the Dharma?
By reason of his previous habit, he finds pleasure in,
  and aspires to absence of turmoil; he does not have the courage to apply
  himself to making others understand the profound Dharma: he would have to make disciples; he would have to conduct the multitude who
  follow the current against the current, and this is a difficult thing. Now
  he fears being distracted from his absorption and of entering into
  contact with humans.

My commentary:
A Pratyekabuddha has understood and pierced through his/her own obstacles (defilements, obscurations). He does know how he himself achieved Enlightenment. But in order to teach others one must pierce through the veils of million other combinations of karma and defilements that other beings may have. That's the difficult part.
Plus, because Enlightenment is non-conceptual, explaining it with concepts may seem like heaping further B.S. on top of existing heaps of B.S. Very burdensome and not always rewarding. Effectively, for the time you teach you have to step out of Nirvana and back into the pain of Samsara or at least on the edge.
For Pratyekabuddha teaching is both difficult and a pain in the butt, so it is absolutely not worth the effort.

user18: Because they themselves don't know. It's not like when you become enlightened you automatically understand what happened; the only necessary difference is that you no longer have any craving for anything. Actually understanding how you got there takes a much greater degree of wisdom.
It's much like having an epiphany - you realize something about your life, but you don't likely know what exactly you did to give rise to that realization.

4821: <p>I mean I don't know if they do but apparently private buddhas don't put forth a teaching, so my question is why can't they just tell people what they did to attain enlightenment.</p>
 5676: <p>If I remember well, in the gelugpa school of Tibetan Buddhism, private buddhas are synonymous with "small arhats", that have attained the "small nirvana", if they renounce it, they can go on and remove the first veil, at which time they become "aryas", and then the three others, at which time they become buddhas, alias fully awakened, alias "great arhats". </p>

<p>Somehow private buddhas blocked their sufferings without removing the causes, and their state is an intermediary stage for those who want to reach buddhahood for the benefits of others and themselves.</p>
 4742: <p>One difference between a Sammasambuddha and Paccekkabuddha is that, the former, at a point of been capable of achieving Enlightenment, postpones his Enlightenment so that he can become a Bodhisattva to instruct and inspire many beings during many life times, and thus help a large number of beings eradicate craving (the origin of suffering). Thus over the supposedly billions of lifetimes as a Bodhisatva the Bodhisatva gets to know and learns about the various tendencies of the multitude of beings  s/he instructs, and thus is able to preach the dhamma accordingly. The latter had no such intention, and no such training in teaching. That is not to say that Paccekabuddhas are incapable of giving any instruction or inspiring others. However, the body of teaching is not comprehensive or complete like a Sammasambuddha. </p>
 3551: <p>Also forgive me,I forgot where I read this but a pacekabuddha lacks the ability to teach like a supreme Buddha.Even the Buddha after his enlightened almost didn't teach the dhamma because he said it was too hard for us to understand.so I imagine it would have been much more difficult for a private Buddha to teach the dhamma.Especially when its never been heard before or not in a Buddha sasana.</p>
 295: <p>There is another view on why private Buddha's cannot teach.</p>

<ul>
<li>A disciple understands the fabrication pertaining to ones own aggregates</li>
<li>A private Buddha understand above plus fabrication of nature but not that of other beings (some private Buddhas realise Buddhahood through observing nature than oneself)</li>
<li>A fully enlightened Buddha also understands the fabrication pertaining to the aggregates of others also, hence is able to provide and set out proper guidance a tame others who are ready to be tamed.</li>
</ul>

<p>If you do not understand how fabrication work pertaining to another being you cannot give advice on how to come out of the process of creating new fabrications and put a stop to it.</p>

<p>There are documented cases in what they did to realise Nirvana but many are not readily usable by any one who is not mature enough. E.g. looking at a leaf fall fall from a tree, looking at the flow of a stream, etc. It is unlikely anybody else utilise this kind of advice to gain benifit.</p>
 43: <p>They do know. They're just not comfortable with teaching.</p>

<p>In Chapter III, karika 94c of Abhidharmakosabhasya, Vasubandhu explains that Pratyekabuddhas do not teach others because teaching Dharma requires pushing the students "against the current" to "make them understand the profound Dharma", which "is a difficult thing" and causes "turmoil" to Pratyekabuddha, who finds pleasure in the peace of Jhanas and is averse to human contact with its trouble:</p>

<blockquote>
  <p>Why does he not apply himself to the conversion of others? He is certainly capable of teaching the Dharma: he possesses the comprehensions, he can remember the teachings of the ancient Buddhas. He is no longer deprived of compassion, for he manifests his supernormal power with a view to being of service to beings.  He can no longer say that beings are "unconvertible" in the period in which he
  lives, for, in this period—the period of decrease of life—beings can detach themselves from The Realm of Desire by the worldly path. Why then does he not teach the Dharma?</p>
  
  <p>By reason of his previous habit, he finds pleasure in,
  and aspires to absence of turmoil; he does not have the courage to apply
  himself to making others understand the profound Dharma: he would have to make disciples; he would have to conduct the multitude who
  follow the current against the current, and this is a difficult thing. Now
  he fears being distracted from his absorption and of entering into
  contact with humans.</p>
</blockquote>

<p>My commentary:</p>

<p>A Pratyekabuddha has understood and pierced through his/her own obstacles (defilements, obscurations). He <em>does</em> know how he himself achieved Enlightenment. But in order to teach others one must pierce through the veils of million other combinations of karma and defilements that other beings may have. That's the difficult part.</p>

<p>Plus, because Enlightenment is non-conceptual, explaining it with concepts may seem like heaping further B.S. on top of existing heaps of B.S. Very burdensome and not always rewarding. Effectively, for the time you teach you have to step out of Nirvana and back into the pain of Samsara or at least on the edge.</p>

<p>For Pratyekabuddha teaching is both difficult and a pain in the butt, so it is absolutely not worth the effort.</p>
 18: <p>Because they themselves don't know. It's not like when you become enlightened you automatically understand what happened; the only necessary difference is that you no longer have any craving for anything. Actually understanding how you got there takes a much greater degree of wisdom.</p>

<p>It's much like having an epiphany - you realize something about your life, but you don't likely know what exactly you did to give rise to that realization.</p>
