Salayatana is the biggest problem of any mode of Dependent Origination.
For exapmple take the the standard formula:
Avjjyaya Paccaya Sankhara.
Before Avijja this Namarupa body with six senses is already there.
Say take example of me:
I have my Namarupa body with Salayathana.
I am ignorant of four noble truths.
So I accumulate kamma
As a result of my kamma it produce re-birth consciousness. (attachment and aversion)
Then I crate Nama-rupa (perhaps this is new Nama Rupa)
Then I make Salayatana.??? (this is a problem because I already have my body)
The biggest problem (and the only one you can really do anything about) is ignorance. Everything else is conditioned by ignorance. Apart from cessation of ignorance there is absolutely nothing you can do about this entire mass of suffering. When the root condition falls, the rest falls.
True. But practically, if we think of this like a massive tree, cutting only the root wont work (unlike perhaps in real trees). The cutting starts at all levels from the tips of leaves, to the trunk to the root- what ever we can access using sila, samadhi and panna, as and when they present themselves, in the present.
‘Salayatana’ is probably omitted in this mode of Dependent Origination because this mode of Dependent Origination appears to be a later-day concoction for propagation to & conversion of Brahmans.
There have been a number of discussions on Sutta Central, which I recall included Ajahn Sujato’s agreement, that much of the DN, including DN 15, was probably composed for propagation to & conversion of Brahmans.
Thus, nama-rupa in DN 15 appears to have the Brahmanistic meaning. In other words, the ‘salayatana’, most specifically sense objects, are possibly included within ‘form’ (‘rupa’).
In Brahmanism, ‘nama’ was the naming of ‘forms’ (the sense world).
Nāmarūpa-vyākaraṇa (Sanskrit: नामरुपव्याकरण ), in Hindu philosophy, refers to the process of evolution of differentiation into names and forms i.e. to the unfolding of the primal state into the manifest world prior to which unfolding there was nothing that existed… In the Upanishads this term is used to indicate the self-willed manifestation of Brahman under visible and nameable aspects, to the said manifestation into the fictitious plurality of the phenomenal world…
The sage of the Chandogya Upanishad regarded the creation of the universe as a huge chest/egg from a Primeval Being existing as the undifferentiated whole, who alone existed without a second prior to the commencement of the process of creation which was the beginning of the differentiation of the undifferentiated. “The Primeval Being reflected, let me be many, let me produce; having bethought, thus to itself, it produced fire which produced water and from water was produced the Earth (food or matter)” (Chandogya Upanishad VI.ii.1-4). The doctrine of Trivritkarana, the prototype of the doctrine of Panchikarana that tells us how matter came unto existence originating from the primordial five subtle elements , belongs to this Upanishad. From the subtle elements were produced all gross elements, and all matter having names and forms that makes-up the entire universe.
Let me outline the way I see that this is to be understood. I’m going to be using the Suttanta definition of name & form where name is defined as contact, feeling, perception, intention, and attention, and form is defined as the four great elements.
Now first we need to understand the bi-directional relationship between consciousness and name & form. Let me give a concrete example that will make this relationship clear.
Consider the word “ANICCA”. In order for consciousness of the word “ANICCA” to arise, the name & form of all of the individual letters need to arise separately. A, N, I, C, C, and A are all distinct forms. Contact, feeling, perception, intention, and attention need to arise for each letter in the word separately to identify them. Consciousness of the compound “ANICCA” can only arise taking the (name & form)s of all the individual letters as a condition. So we see that name & form is a condition for consciousness. Similarly the name & form of each individual letter could not have been discerned if consciousness didn’t arise (separately) for each of them. Thus we see that consciousness is a condition for name & form.
Applying this principle to the sense bases: In order for consciousness of “the body” (or any other sense base) to arise, first name & form needs to arise separately for all the different minute parts the body consists of. Then and only then can a body (or any other sense base) be discerned.
This is how the interplay between consciousness and name & form gives rise to the six sense bases. This is how the delineation between the internal and the external is established.