Macrocosm and microcosm refers to a vision of cosmos where the part (microcosm) reflects the whole (macrocosm) and vice versa. It is a feature "present in all esoteric schools of thinking", according to scholar Pierre A. Riffard. It is closely associated with Hermeticism and underlies practices such as astrology, alchemy and sacred geometry with its premise of "As Above, So Below".
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. In physics, scale invariance describes the same phenomenon, although the universe as a whole is not physically scale invariant according to the modern understanding. However, scale invariance does appear in some physical systems, such as electrical breakdown.