yasmaat tu tasmin na sukhaM na duHkhaM
jNanaM ca tatr’ aasti tad-artha-caari
nirucyate dhyaana-vidhau caturthe
Since in this there is neither happiness nor suffering,
And the act of knowing abides here, being its own object,
Therefore utter lucidity
through equanimity and mindfulness
Is specified in the protocol for the fourth realisation.
Line 1, as I read it, is saying that body and mind dropping off is neither something positive nor something negative.
And, Line 2 suggests, neither is it quite true to call it nothing.
The utter lucidity expressed in Line 3, then -- like fish swimming like fish, or like birds flying like birds -- is not really something and not really nothing.
In thinking how to translate Line 4, I remembered a recorded talk of Ajahn Sumedho that somebody gave me, on a cassette, when I was in Thailand in 1988. Sumedho joked that Theravada Buddhism was “a clinical religion.” Sumedho's wry humour may be somehow relevant to this line, in the sense that the path trodden by the elders was not wishy-washy philosophy: it was rather a path on which distinct, practical criteria were enumerated.
In a similar clinical spirit, I am going now to tick the final box on my four vestibular reflexes agenda. I have discussed already the relevance of the Moro Reflex as a centre of emotional desire/longing/grasping, the Tonic Labyrinthine Reflex as having to do with balance, and the Asymmetrical Tonic Neck Reflex as having to do with pointing oneself in a particular direction; and I have related these functions to Ashvaghosha's description of Nanda's progress through the stages of realisation. The fourth of the four vestibular reflexes, to which I come now, is the Symmetrical Tonic Neck Reflex.
The mental sitting that Ashvaghosha has described from verse 17.42 onward, as I understand his description, is opposed to the kind of instinctive physical sitting that a monkey might practice.
One of the things that differentiates human beings and monkeys is inhibition of the cat-sit reflex (in neurology, the STNR: Symmetrical Tonic Neck Reflex). When the neck of a monkey, or a cat, or a 6-month old infant, is extended, the cat-sit reflex causes the hips and knees to want to bend. (For illustrations, follow this link.) The reflex therefore enables the infant to pull himself up into the cat-sit position. The same reflexive tendency prevents monkeys from being able to stand fully upright -- when a monkey’s neck is extended, its hips and knees tend to remain slightly bent. In the natural course of human development, the STNR becomes fully inhibited, mainly by the act of crawling on all fours, and then by cross-pattern walking and other upright activities, so that a mature person, unlike a monkey, becomes able to stand with 360 degree poise, fully upright.
What Ashvagosha is describing in this verse, as I read it, is the culmination of mental sitting, which is coterminous with inhibition of the four main vestibular reflexes and in particular with conscious inhibition of the fourth of the four reflexes, the STNR.
Until the STNR is fully inhibited, we are not fully liberated from monkey-like tendencies. In that case, we still have further to go before realising the fully conscious action that Ashvaghosha is describing here -- the clear and simple awareness of just sitting upright.
tu: but (or just for emphasis)
tasmin (locative): in it
jNanam (accusative): knowing, the act of knowing
artha: aim, meaning, object, thing, wealth, treasure, substance
caari = nominative/accusative of caarin: (at the end of a compound) moving, walking or wandering about, living, being, proceeding
upekSHaa: indifference, equanimity
smRti: mindfulness, attentiveness, awareness
parishuddhiH: complete purification; absolution, rightness
nirucyate = passive of nir + vac: to speak out, express clearly or distinctly, declare, interpret, explain
vidhau (locative of vidhi): direction, rule, formula, outline; any prescribed act
caturthe (locative of caturtha): in the fourth
And since in it there is neither bliss nor suffering and knowledge there fulfils its aim, therefore in the process of the fourth trance there is explained to be purification through indifference and attentiveness.
Since there is no bliss or sorrow at this level, knowledge lives here at one with its object; therefore in the description of the fourth level of meditation it is said that there is purification of equanimity and mindfulness.