when we talk of emergent behavior, when we talk of interpreters and languages, when we talk of people as made of cells, when we talk of chemistry as above physics, we are talking about layers.
Turchin, one of the originators of MSTT previously did research on Supercompilation, a generalization of Partial Evaluation with the same objectives. (see proposal).
as programmers try to provide higher levels of abstraction (more power), programming systems over time usually climb a chain of generalizations. layers are added on top, and intermediate layers (languages) appear.
difference between engineered languages and naturally evolved ones.
we divide the world we see into layers: disciplines with self-consistent rules that we can understand. some of these are only approximations---we've idealized.