Do you have any suggestions for how to continue to benefit from the Heart Sutra's view of utter liberation: that “there is nothing here that threatens, there is nothing to be defended,” while following the imperatives of ethics, while caring for the body-mind of self and others involved for now in this karmic process? I can see that both views are true in theory, but they strike me as contradictory in practice--I seem to be able to focus on only one view at a time. So how to resolve, or investigate, what I experience as this tension between compassion that leads to the desire to prevent or alleviate suffering in the world of mundane specificity (form) and the movement of compassion, as embodied by Avalokitesvara and the Heart Sutra, to free human beings from our (biologically generated (?) and profoundly embedded) mistaken perceptions of “our” relation to those forms?
The short answer to your excellent question is this:
The precepts are themselves a description of the way karma and the other principles of reality really work.
To say more:
When you know that the thing you think is your self is merely an aggregation of elements and energy, then you also know that you are literally what you think, do and say in any given moment, and you are the consequences that unfold from that. So you take care because you know how the body and mind and karma really work. Yet you are also free of that, because you can live in absolute harmony with it, not pushed and pulled.
To add a bit more:
When you taste a bit of the three marks of existence - impermanent, empty, and fundamentally unsatisfactory (dukkha) - then a strong sense of compassion naturally wells up for yourself and others who are entangled by these principles without fully seeing or understanding them. You want to help the clarity to develop and the dukkha to stop. This turns you deeper and deeper toward practice, which happens in the midst of a mundane world, which itself is the expression of the principles.
To see it this way is to see that the precepts and concepts and meditation experiences that we're studying are themselves describing a way of living that cares for the body as a vehicle for clarity, and cares for self and others by not enacting harm, and cares for the world by being aware of consequences. These practices keep turning your mind and body toward the insights that keeping generating compassion, and so on, and so on. Finally, when you fully realize the principles and drop the illusion of self, there is total clarity about the nature of interconnection, even while the need to define one's self relative to others has gone away.