Basically it once again relates to the continuous detachment from an over-identification with the "higher" spiritual aspect of personality, so as to eventually allow equal emphasis to be given to the corresponding "lower" physical aspect. For in truth both are fully complementary - and ultimately identical - with each other. So in an equivalent manner, one is here recognising the need to fully harmonise transcendence (as spirit beyond all form) with immanence (as spirit prior to and thereby inherent in all such form).
Now, one might indeed query to what extent distinct levels of development are even appropriate at this stage of development.
It is important to bear in mind that I always use the notion of discrete stages in a relative dynamic manner, where they remain necessarily continuous with all other stages of development.
At this point, the continuous aspect is - relatively - of much greater importance, whereby one ceaselessly integrates in a two-way interactive manner both the "higher" and "lower" levels (especially with respect to Band 3 and Band 1 respectively).
However a certain discrete element is also necessarily in evidence (relating as we have seen to the - still - dominating influence of the "higher" stages). So to this extent, we can still refer to a (relatively) distinct level!
It is only when this process is completed with respect to all the levels of Band 4 that one can finally enter a state which is truly without stages (where "higher and "lower" levels are fully integrated).
However, even this quickly gives way to a new enhanced experience of "radial" reality in a refined phenomenal manner. And this can again be identified with many further stages that have a discrete meaning in a refined relative manner.
When Level 2 (Band 4) has run its course, a remarkable transformation can then unfold in personality.
In the Christian mystical literature this is sometimes referred to as "Deification", which reflects the relatively transcendent aspect (whereby one now fully realises one's individual as inseparable from the divine personality i.e. God). Perhaps, more commonly it is referred to as "Spiritual Marriage" reflecting the complementary immanent aspect in the more social experience of loving union with the other (recognised now as inseparable from one's self). In psychological terms, this could be well expressed as the union of both masculine and feminine principles within one's psyche.
However I prefer to look on it as the enhancement of reality, whereby the ordinary can be seen as extraordinary and the extraordinary in like manner as ordinary. In other words one has consolidated in experience a habitual state that is now commonplace, whereby phenomenal reality continuously mediates spirit.
In terms of Euler's identity, Level 3 can be expressed as the two-way interaction of both Levels 1 and 2.
Again Level 1 is represented as e2iπ = 11 and Level 2 as e – 2iπ = 1 – 1 respectively.
Therefore multiplying both expressions,
e2iπ * e – 2iπ = 11 * 1 – 1.
Thus by adding indices on both sides,
e0 = 10.
And this is the appropriate holistic mathematical expression for Level 3.
What this means in effect is that - whereas one initially experienced ultimate reality in transcendent terms as unity beyond all form - one now understands it in a complementary fashion as nothingness (i.e. emptiness). This in turn is associated with the corresponding immanent experience of ultimate reality as the unity prior to and thereby inherent in all form.
In fact we have here the holistic mathematical expression of what is famously expressed in the buddhist sutra,
"Form is nothing but Emptiness
Emptiness in nothing but Form"
In other words, the ultimate unity of all (phenomenal) form is inseparable from nothingness.
Nothingness is inseparable from the unity of all (phenomenal) form.
Thus nondual ultimate reality is a plenum-void or alternatively a dazzling-darkness (which of course is fully paradoxical from a dualistic perspective).
Now, from the standard analytic perspective, 1 and 0 are absolutely distinguished from each other (as distinct units).
This indeed forms the basis of the binary digital system, whereby all information can be potentially encoded in terms of these two digits.
However, we have now come full circle to the pure holistic perspective, whereby 1 and 0 are intuitively seen as fully interdependent with each other.
And just as the (analytic) binary digital system can be potentially used to encode all information, the corresponding (holistic) binary digital system can likewise be potentially used to encode all transformation processes. So 1 can be seen as the representation of linear logic (the logic of form).
0 in turn can be seen as the (indirect) representation of circular logic (the logic of emptiness).
And all development processes can be seen therefore as representing a certain unique configuration with respect to both types of logical systems!