For me the instructions in Sn36.7 fits nicely in to the template of the following verse from the Parayana Vagga,
Whatever streams there are in the world, Ajita,” said the Gracious One,
“mindfulness is the constraint for them.
That is the restraint for streams, I say; by wisdom they are shut off.”
Snp5.2
The first instruction in Sn36.7 is to establish mindfulness. Rest of the instruction probably has to do with seeing or understanding with wisdom rather than direct observation. The streams may be thought of as tendency to greed regarding pleasant feelings, tendency to repulsion regarding painful feelings and tendency to ignorance regarding neutral feelings.
As for ‘kāya’ in this sutta it could stand for the physical body in the following sense,
The Tathagata, knowing directly all stations of consciousness,
Viññāṇaṭṭhitiyo sabbā,
Abhijānaṃ tathāgato
Posala sutta
The word I am interested in above is ‘Viññāṇaṭṭhiti’ or stationing of consciousness . At least in the human realm consciousness stands or is stationed in the physical body. If the body is destroyed even if one in jhana except perhaps saññā-vedayita-nirodha, consciousness will depart the body.
When consciousness is included all the other immaterial aggregates with feeling is included. Since consciousness cannot be defined without them.
This kind of treatment can also be found in
Assutavā Sutta where mind and body is taken as equivalent to the five aggregates,
“Mendicants, when it comes to this body made up of the four primary elements, an uneducated ordinary person might become disillusioned, dispassionate, and freed. Why is that? This body made up of the four primary elements is seen to accumulate and disperse, to be taken up and laid to rest. That’s why, when it comes to this body, an uneducated ordinary person might become disillusioned, dispassionate, and freed.
But when it comes to that which is called ‘mind’ or ‘sentience’ or ‘consciousness’, an uneducated ordinary person is unable to become disillusioned, dispassionate, or freed. Why is that? Because for a long time they’ve been attached to it, thought of it as their own, and mistaken it: ‘This is mine, I am this, this is my self.’ That’s why, when it comes to this mind, an uneducated ordinary person is unable to become disillusioned, dispassionate, and freed.
But an uneducated ordinary person would be better off taking this body made up of the four primary elements to be their self, rather than the mind. Why is that? This body made up of the four primary elements is seen to last for a year, or for two, three, four, five, ten, twenty, thirty, forty, fifty, or a hundred years, or even longer.
But that which is called ‘mind’ or ‘sentience’ or ‘consciousness’ arises as one thing and ceases as another all day and all night. It’s like a monkey moving through the forest. It grabs hold of one branch, lets it go, and grabs another; then it lets that go and grabs yet another. In the same way, that which is called ‘mind’ or ‘sentience’ or ‘consciousness’ arises as one thing and ceases as another all day and all night.
In this case, a learned noble disciple carefully and properly attends to dependent origination itself: ‘When this exists, that is; due to the arising of this, that arises. When this doesn’t exist, that is not; due to the cessation of this, that ceases. That is: Ignorance is a condition for choices.
Choices are a condition for consciousness. … That is how this entire mass of suffering originates. When ignorance fades away and ceases with nothing left over, choices cease. When choices cease, consciousness ceases. …That is how this entire mass of suffering ceases.’
***Seeing this, a learned noble disciple grows disillusioned with form, feeling, perception, choices, and consciousness.***Being disillusioned, desire fades away. When desire fades away they’re freed. When they’re freed, they know they’re freed.
They understand: ‘Rebirth is ended, the spiritual journey has been completed, what had to be done has been done, there is no return to any state of existence.’”
Sn12.61