Macrocosm and microcosm
Macrocosm and microcosm is an ancient Greek Neo-Platonic schema of seeing the same patterns reproduced in all levels of the cosmos, from the largest scale (macrocosm or universe-level) all the way down to the smallest scale (microcosm or sub-sub-atomic or even metaphysical-level). In the system the midpoint is Man, who summarizes the cosmos.
The Greeks were philosophically concerned with a rational explanation of everything and saw the repetition of the golden ratio throughout the world and all levels of reality as a step towards this unifying theory. In short, it is the recognition that the same traits appear in entities of many different sizes, from one man to the entire human population.
Macrocosm/microcosm is a Greek compound of μακρο- "Macro-" and μικρο- "Micro-", which are Greek respectively for "large" and "small", and the word κόσμος kósmos which means "order" as well as "world" or "ordered world."
Today, the concept of microcosm has been dominated by sociology to mean a small group of individuals whose behavior is typical of a larger social body encompassing it. A microcosm can be seen as a special kind of epitome. Conversely, a macrocosm is a social body made of smaller compounds.
See also 
- Republic, Plato, trans. By B. Jowett M.A., Vintage Books, NY. § 435, pg 151
- Theories of Macrocosms and Microcosms in the History of Philosophy, G. P. Conger, NY, 1922, which includes a survey of critical discussions up to 1922.
- Cosmos - an Illustrated Dimensional Journey from microcosmos to macrocosmos - from Digital Nature Agency