Visuddhimagga (English translation by Bhikkhu Nanamoli) XXII.46 quotes from the Path of Discrimination (Patisambidhamagga) as follows:-
"Coupling of the Powers'. At the time of developing the eight mundane attainments the serenity power is in excess, while at the time of developing the contemplation of impermanence, etc., the insight power is in excess. But at the Noble Path moment they occur coupled together in the sense that neither one exceeds the other"
The quote concludes by stating
"He develops serenity and insight coupled together in the sense of emergence (Patisambidhamagga ii,98)".
My understanding of the above is that the yogi needs to develop the method to ensure that coupling occurs at the Noble Path Moment.
My question is anyone able to throw some light on this coupling from the scriptures or from some other source or from personal experience?
Discovered later that a possible answer to this question may be found in "Foundations of Tibetan Mysticism" pdf by Lama Govinda' p. 175. where reference is made to three zones viz. Earth (materiality), Universe and Human. The Human Zone is the plane of ''individual realization in which the forces of the earth and the universe become conscious in the human soul as an ever present and deeply felt reality'. If Earth and Universe could be related to Samatha and Vipassana we may be homing in on a solution to a problem that has bedeviled many a good yogi-that of coupling (yuganaddha) both these entities to realize Nibbana. Would appreciate a feedback, especially from those who are familiar with Vajrayana and ''Buddhist Kundalini'' energies.