The mind cannot generate stable unity of knowing, or even permanently let go of its struggle to do so, as its very nature is polarizing. Neither can the observer "I" sustain itself continually as a creator outside of these polarities arising from the senses, or even as a permanent "gaze" within the present moment.
The reason for this instability is that the present moment and the eternal aren't the same, as the former adheres, and arises, dependently within the latter.
Unity would be the only state in which internal dialogue (id), or polarity expressed in mental experience, isn't predominating; yet nowhere in the created order do we find polarities stabilizing or permanently dissolving into a dyamic unity of consciousness, as the unifed principle, to be real, must transcend them to uphold their existence. The mind cannot create grace, or anything out of nothing for that matter (so to speak).
The continguency of the present moment upon the eternal is reflected in the mind's fragile ability to remain outside of time. The reason the id cannot be resolved except in brief moments is that the polarities driving it (as passion in the body and unintended/automated talk in the head) embody the separation of creature from Creator, the fallen character of having sought knowledge outside of grace, and therefore outside the original purpose of human existence.
The central channel, or sushumna nadi, was originally meant, in the pre-fallen creature, to embody mind-body unity, with polarities dissolving, via consent of the soul, into a communion of praise, gratitude and love, but only with a created kundalini completely under the command of the uncreated Holy Spirit, which is now for us the work of Christ's resurrected body in the Eucharist via the communion of the Holy Trinity, and after death as the beatific vision.
These struggles and limited abilities of the mind are all signs of our fallen nature, with no antidote to be found in Buddhism, as the actual dying process doesn't lend itself to meditation, but only to the grace of prayer and surrender which the mind cannot replicate.
