I’ve been researching samādhi and jhāna in the early discourses lately in an effort to set others’ interpretations aside and form my own impression of how these concepts were understood in Early Buddhism. I’m not arguing here for or against any specific interpretation but would like to share some of my evidence, as it relates to the OP. There are a couple of comments indicating my impression of the evidence, but that’s all it is – just my impression so far, open to adjustment.
The stock description of the jhānas given in the OP uses the word kāya for body. Some have interpreted this as meaning “body of mental factors” (i.e., the whole mind). There are indeed suttas where the Buddha used the word kāya in a way that can’t be interpreted as the physical body. For example, in the suttas from AN 9.43 to AN 9.61 he describes the kāyasakkhi , the “body witness” (Ven. Bodhi) or “personal witness” (Ven. Sujato), which is one who attains the four jhānas, the four formless states, and cessation of perception and feeling. For each of these nine states, it is said that the person
“ Yathā yathā ca tadāyatanaṃ tathā tathā naṃ kāyena phusitvā viharati .”
“He dwells having contacted that base with the body in whatever way [it is attained].” (Bodhi)
“They meditate directly experiencing that dimension in every way” (Sujato)
It seems clear from many suttas that one no longer experiences the physical body in the formless states (and certainly not in cessation), so kāya, in these suttas, can’t mean physical body.
On the other hand, the stock phrases describing the four jhānas and the similes referred to in the OP do seem, to me, to refer to physical experience.
Also, in MN 119 (Kāyagatāsati Sutta) the four jhānas are listed as one of the ways of developing mindfulness of the body, alongside the other methods, which are clearly concerned with the physical body.
As far as I’ve been able to find, here are the bits of sutta evidence that describe the first jhāna:
- Secluded from sense pleasures (kāma)
- Secluded from akusala states
- With vitakka vicāra
- With pīti sukha from seclusion (MN 4, et al)
- Detachment/seclusion from attachments/possessions (upadhiviveka)
- Complete calming of bodily disquiet (kāyaduṭṭhullānaṃ); this may refer to ‘body tranquil, untroubled’ in MN 4, and ‘body becomes calm’ in MN 7 and MN 40 (MN 64)
- Makes the pīti sukha drench, steep, saturate, suffuse whole body; like skilled bath man sprinkles bath powder gradually with water, kneads it, soaks it (MN 39, DN 2)
- 5 factors: vitakka, vicāra, pīti, sukha, ekaggatā (one-pointed, unscattered)
- 5 factors abandoned: 5 hindrances (MN 43)
Vitakka vicāra that hasn’t ceased is the agitation there (MN 66)
- When one attains the pīti sukha that is secluded from sensual pleasures and akusala states, or to something even more peaceful, hindrances, discontent, laziness don’t invade mind (MN 68)
- Akusala thoughts/intentions (sankappa) cease, but kusala thoughts/intentions continue (MN 78)
- Speech has ceased (SN 36.11)
- Perceptions of sensuality (kāmasaññā) have ceased (AN 9.31)
- Previous kāmasaññā cease; there is subtle/fine (sukhuma) and real/true (sacca) perception of pīti sukha born of seclusion (viveka) (DN 9)
I haven’t found any sutta that describes the body dropping away in the first jhāna. It seems to me that would be a significant change to one’s experience and would warrant mention.
However, descriptions of the first formless state (sphere of limitless space) do seem to be explicit about the body and senses dropping away, which may indicate that this is when it happens:
- Completely passing beyond all perceptions of form (rūpasaññā)
- Perceptions of sensory impact (paṭighasaññānaṃ) disappear (MN 25)
Rūpasaññā has ceased (SN 36.11, AN 9.31)
- Previous perception (of rūpasaññā) ceases, one has subtle and real perception of sphere of limitless space (DN 9)