The SMS - simple model of spirituality - has these parts:
- A physical body, of an individual human being;
- a transcendental entity, "inside" 1;
- an interface - practically unlimited - between 1 and 2, a non-physical part inside 1, yet different from 2;
- the world outside 1 (the physical body), including living and non-living things. That includes other humans as well.
In Mind Sandwich, I talked about a single entity or field which is different at different levels or at different boundaries, next to two very different entities. This single field could be considered a communication channel - a pipe - or a layer between those two entities.
In communication networks, such a channel or pipe is a router or gateway, one that transforms one type of communication into another. For example, data sent in wireless mode changed to wired mode. Or vice versa.
Now imagine a similar thing exists inside you. Indian philosophy calls it antaḥ-karaṅa, literally, inner instrument. It is also translated as mind, intellect, ego, etc., depending on its function or mode. This inner instrument has two boundaries or interfaces or ends, one near a transcendental entity that subsumes the physical and spiritual universes, and one near the physical body.
Spiritual practice simply aims to activate the entirety of this inner instrument, especially the parts closer to the transcendental entity. Those parts are much, much, subtler than the parts closer to the physical body. Increase in subtlety comes with fewer and fewer qualities related to individual and separated entities. Thus, from selfishness - for one entity, or a limited set of entities related to that one entity - to selflessness - away from one or a small set of related entities, towards all entities.
The inner instrument translates communication from the transcendental entity to the physical body. But, since it carries out other functions like memory, ego, discrimination, emotion, etc. for the physical body, in contrast to the router, it also uses the communication in its own activities.
Different paths focus on different levels of the antah-karaNa. advaita, to take an extreme example, focuses only on the transcendental entity and the subtlest parts nearby, much to the detriment of the rest of the interface. cārvāka - the favourite whipping post of other Indian philosophies - is at the other extreme, focusing only on the physical body and very few parts of the antaḥ-karaṅa nearest to it.
The Patanjali Yoga Sutras take a three-pronged approach.
At the lowest level is the eight-step process - aṣṭānga yoga, including outward-oriented or other-oriented moral and ethical practices, as well as sensor- or boundary- (skin, ears, etc.) oriented, and inward-oriented practices which train the attention to face three different directions - outward, at the instruments, and inward.
At the middle level is the three-step process of kriya yoga, including austerity or reducing over-indulgence, self-study (of and by oneself), and feeling the presence of the transcendental entity at various levels of delimitation.
At the highest level is the unnamed two-step process of going directly from the grossest to subtlest levels of the interface - antaḥ-karaṅa - through the practice of stabilising or holding it at different levels of subtlety, and letting go or relinquishing grosser levels. That transmutes a grosser level of antaḥ-karaṅa into its subtler causal level. At the highest or subtlest level, the antaḥ-karaṅa becomes unmanifest for a single human being.
The higher levels become habitual, effortless, and effective only after the lower levels have been mastered. Those who want to do only the subtlest practices, a-la advaitins, risk getting subtler states randomly and definitely have trouble maintaining them.
(Along similar lines, Idries Shah writes that Sufi training emphasises practices for emotional stability first in order to reliably - and repeatedly - get and keep veridical - true inner - experiences.)
NOTES
The three levels of practice are based mainly on Swami Veda Bharati's translation and commentary on the Yoga Sutras. Any mistakes in interpretation or paraphrasing are mine.
