I think one of the main ideas of science is that all physical effects can be explained eventually. In science there is no concept of a physical effect or part of the natural world which can't be explained by science. In science, there is no "energy" which is beyond the eventual ability of science to measure and define it. Science does not deal with the supernatural, that is, effects outside of or beyond the natural world. Subjective experiences which can't be replicated, observed by others, or measured and documented don't find their place in science. And I think this is why spirituality doesn't have a place in teaching permaculture. Spiritual experiences are subjective, permaculture seems to be an objective design science.