You see, "Mu" is an ancient Zen answer which, when given to a question, UNASKs the question. Here, the question seems to be, "Should the world be under stood via holism, or via reductionism?" And the answer of "MU" rejects the premises of the question, which are that one or the other must be chosen. By unasking the question, it reveals a wider truth: that there is a larger context into which both holistic and reductionistic explanations fit. See the principle of inclusiveness in Epistemology.

Ideas of hyperreality, chaos magik, Zen, etc.

Etymology

I think it comes from a mathematical notation which uses $\mu$ to denote "free" searches (searches without bounds). See page 424 in GEB