What is the medium by which karma is carried from moment to moment, and lifetime to lifetime? What is it that creates this continuity?
Bhikkhu Bodhi: It is a stream of consciousness, a continuum of moments of consciousness. As each moment of consciousness perishes, it passes its entire accumulated storage of impressions, experiences, potentially memories, and karmic deposits on to the succeeding moment of consciousness.
Within a single lifetime, that continuum of consciousness rests on the basis of a physical body. When death takes place, the physical body can no longer serve as the basis for the continuity of consciousness. But as long as latent tendencies of ignorance and craving still exist within that stream of consciousness, it will re-arise after death using some new physical organism as its basis. (There are formless realms where the continuity of consciousness can occur without a physical basis, but we need not discuss those here.)
The underlying latent defilements—in particular the craving for new existence (Pali, bhava-tanha) and behind that, ignorance (Pali, avijja)—maintain the continuity of consciousness from life to life. When death takes place, ignorance and craving renew the process of conditioned existence. The stream of consciousness preserves and transmits all the wholesome and unwholesome karmas generated by that being, not only in the immediately terminating lifetime but from beginningless time. All the karmas whose force has yet to be expended will be transmitted.
Jan Chozen Bays: What carries karma forward is the energy of the three poisons: clinging, aversion and ignoring. As a pediatrician, I have examined hundreds of newborn babies, and each one of them has these characteristics. Some are born angry and upset at the world. Others are born wanting sense experiences and are upset if they don’t get them. Still others just like to go unconscious, and if distressed, they go to sleep. These same energies bond human existence together moment by moment. But if we can experience our life as individual moments, as occurrences within a framework of emptiness, there is no difficulty and in that moment karma is not transmitted.
Someone said that when you sit very deeply, at least you are doing no harm. One of our early precepts in Zen is, “First cease from evil.” When you sit in absolute stillness, you stop transmitting the karmic streams that are moving through you all the time. If my parents abused me and therefore I carry aggressive energy that wants to strike out at others, I can nevertheless create a gap through my practice, so that when the impulse to become angry arises, I don’t carry it out in speech and action. I have expiated not only my own karma but also my parents’ karma. That is the most wonderful aspect of karma: it spreads out from us in all directions throughout space and time. We are made of emptiness and karma.
Jeffrey Hopkins: In the teachings, there are descriptions of a mind basis of all, the alaya-vijnana, that serves as a medium for karma. There are also descriptions of a subtle mental consciousness that serves as the medium for the infusion of karma. And then interestingly, there is the description of the person as the medium of karma, which is rather fascinating.
The emptiness of persons doesn’t mean that persons don’t exist. Persons do exist. We exist as dependent arising. When we say things like, “I finally owned up to what I did,” there is the sense of “I did it.” I often pause to catch myself seeing the locus of owning the action as “I.” That’s very provocative. Not much is said about it, but it is widely known that this is another way of talking about the medium of karma.
Then there is another view, which is that the mere ending of the action is in itself a sufficient medium. It is an impermanent phenomenon that goes on and on until it brings about the result of that action. This is perhaps the most mysterious of them all.
Finally, in highest yoga tantra, there is the extremely subtle mind of clear light which serves as the basis and carries the previous positions from lifetime to lifetime.
I should add that the stopping of ignorance and attachment that has been discussed here doesn’t necessarily bring about the end of embodiment. But it would put one in a state where one would be called to unleash the energies of all of those karmas and turn them into buddhahood.