Emergent phenomena fascinate me.
Structures that emerge from interaction of independent agents surround us at any time and at any order of magnitude. Sand grains interact to form dunes and beaches, cells interact to form living creatures and a broad range of social phenomena emerges from the interaction of individuals.
Similar but not identical.
Even if their creation follows the same rules, two structures created in such a process are hardly ever completely identical: No two trees ever have exactly the exactly the same branches even if the underlying mechanisms of branch formation are the same. This distinguishes nature from man-made structures, which are typically built in a “top-down” manner according to a plan that exactly describes the end-product.
It’s these endless variations of the same themes of nature that I miss when I spend a large fraction of my time in environments dominated by industrial mass production.