It would be helpful to take a look at the etymology of the word and see how it fit into a dominant pre-Buddhist world view - this will give a clue as to why the suttas identify sakkāya
with the Suffering of the First Noble Truth.Sakkāya
(reflexive pronoun = one's own) + kāya
So, what's the big deal about one's own body? Why should a view about it be so pernicious, when SN 12.61 suggests that decay in the physical body can be so easily discerned? I would suggest that kāya
has a very broad range of meanings, including the physical body, but more importantly, also the Vedic sense carried by the Upanisads. And it is this Vedic sense that comes to be lumped under sakkāyadiṭṭhi
Olivelle says -
In these documents, the term most frequently used with reference to a living,
breathing body is ātman, a term liable to misunderstanding and mistranslating be-
cause it can also mean the spiritual self or the inmost core of a human being, besides
functioning as a mere reflexive pronoun.
p.45, The Early Upanisads, Annotated Text and Translation
Several examples from the Bṛhadāraṇyaka Upanisad make it clear that ātman's
3rd sense as the "body" is used to describe the collection of functions known as the prāṇas
of speech, sight, hearing, mind and breath. A quote from the BA -
Next, an examination of the observances. Prajapati created the vital functions
(prana). Once they were created, they began to compete with each other. Speech
threw out the challenge: "I'm going to speak!" Sight shot back: "I'm going to see!"
and hearing: "I'm going to hear!" The other vital functions bragged likewise, each
according to its function. Taking the form of weariness, death took hold of them; it
captured and shackled them. That is why speech becomes weary, as do sight and
hearing. The central breath alone, however, death could not capture. So they sought
to know him, thinking: "He is clearly the best among us; whether he is moving or at
rest, he never falters or fails. Come, let us all become forms of him!" So they all
became merely forms of him. Therefore, they are called "breaths" (prana) after him.
For this very reason, a family is called after a man in that family who has this
knowledge. So, anyone who competes with a man with this knowledge withers
away. Yes, he withers away and dies in the end.
That was with respect to the body (atman). 22What follows is with respect to
the divine sphere.
pp.57 - 59
(As a sidetrack, MN 44's speech formations, body formations and mental formations are also discussed in the BA - "These are what constitute this self (atman)—it
consists of speech, it consists of mind, and it consists of breath." at p.55)
Yet, this sense of ātman
as body is, according to the BA, incomplete. One is enjoined to realise ātman
as Self, here -
At that time this world was without real distinctions; it was distinguished sim-
ply in terms of name and visible appearance—"He is so and so by name and has this
sort of an appearance." So even today this world is distinguished simply interms of
name and visible appearance, as when we say, "He is so and so by name and has
this sort of an appearance."
Penetrating this body up to the very nailtips, he remains there like a razor
within a case or a termite within a termite-hill. People do not see him, for he is in-
complete as he comes to be called breath when he is breathing, speech when he is
speaking, sight when he is seeing, hearing when he is hearing, and mind when he is
thinking. These are only the names of his various activities. A man who considers
him to be any one of these does not understand him, for he is incomplete within any
one of these. One should consider them as simply his self (atman), for in it all these
become one. This same self (atman) is the trail to this entire world, for by following
it one comes to know this entire world, just as by following their tracks one finds
[the cattle]. Whoever knows this finds fame and glory.
8This innermost thing, this self (atman)—it is dearer than a son, it is dearer
than wealth, it is dearer than everything else. If a man claims that something other
than his self is dear to him, and someone were to tell him that he will lose what he
holds dear, that is liable to happen. So a man should regard only his self as dear to
him. When a man regards only his self as dear to him, what he holds dear will never
The problem of sakkāya
therefore seems to be the tendency to think of this "collective" of functions as something to be realised as Self, be it one that lives on from life-to-life, or which terminates at death.
PS - Makes you wonder how the other instances of kāya
in the suttas ought to be interpreted, eg he dwells touching the formless etc etc liberations with his body (kāyena
)... See Tse Fu Kuan's note about the the Chinese parallel to MN 119, where the kāya
that is perused looks more like the Vedic "body" that includes mental states (Mindfulness in Early Buddhism, pp 82-83).