Why five aggregates instead of just three? If feeling, perception and consciousness are conjoined or mixed, and it is not possible to separate them or delineate them or disjoin them, then why do we have five different aggregates instead of just three?
What is the significance and usefulness in the teaching to have feeling, perception and consciousness clearly distinguished into three different aggregates? Why were they not combined into a single aggregate?
From MN 43 (translated by Ven. Thanissaro):

&quot;Feeling, perception, &amp; consciousness are conjoined, friend, not
disjoined. It is not possible, having separated them one from another,
to delineate the difference among them. For what one feels, that one
perceives. What one perceives, that one cognizes. Therefore these
qualities are conjoined, not disjoined, and it is not possible, having
separated them one from another, to delineate the difference among
them.&quot;

From MN 43 (translated by Ven. Sujato):

“Feeling, perception, and consciousness—these things are mixed, not
separate. And you can never completely dissect them so as to describe
the difference between them. For you perceive what you feel, and you
cognize what you perceive. That’s why these things are mixed, not
separate. And you can never completely dissect them so as to describe
the difference between them.”
Very good question, which i imagine i will post more about at a later time.
Firstly, about the translations, I suspect the translations of &quot;paññāpeti&quot; as &quot;delineate&quot;, &quot;describe&quot; or &quot;declare&quot; may possibly be questionable. &quot;Paññāpana&quot; (from &quot;paññāpeti&quot;) is found in SN 22.82 and taken by Bhikkhu Bodhi to mean &quot;manifestation&quot;, which fits the context of SN 22.82. Therefore, substituting into MN 43, it might read as: ???????
Secondly, the three types of feelings are related to the arising of the three types of defilements, such as explained in paragraph 30 of MN 148. Therefore, it appears most essential to highlight the feeling aggregate. As said in paragraph 15 of AN 3.61:

Now it is for one who feels that I proclaim: ‘This is suffering,’ and
‘This is the origin of suffering,’ and ‘This is the cessation of
suffering,’ and ‘This is the way leading to the cessation of
suffering.’

Again, AN 10.58 says:

vedanāsamosaraṇā sabbe dhammā
All dhamma practices converge/meet on feelings.

As we understand by MN 148, MN 38, MN 37, AN 3.61, etc, feeling can arise without there being the arising of craving and suffering. Before the Buddha, I imagine people were seeking a nirvana that was without feeling. Even today on the Buddhist internet, we witness individuals posting obsessively and mistakenly about the cessation of perception &amp; feeling as though it is Nibbana. But the Buddha declared the only possible here-&amp;-now Nibbana and Liberation cannot be without feeling. Therefore, it appears essential to the Buddha-Dhamma, as already explained, to highlight the importance of feeling.
Also, there are conscious experiences that are predominantly feelings, such as jhana. While consciousness arises &amp; lands on such pleasant jhana feelings, obviously the feeling aggregate starts apart in and dominates such jhana consciousness.
Thirdly, as for &quot;perception&quot;, at least in relation to what is 'supramundane', there are many suttas about perverted perception and enlightened perception, such as AN 4.49 and AN 10.60. Therefore, it appears to highlight the perception aggregate is also important and it needs to be distinguished from consciousness and feeling.