Monadology is a philosophical work by Gottfried Wilhelm Leibniz, written in 1714. It presents a metaphysical system where the universe is composed of simple substances called monads. These monads are indivisible, unique, and reflect the entire universe from their own perspective, functioning like tiny, self-contained entities. In Monadology, Leibniz argues that monads do not interact with each other directly but are pre-established to harmonize with one another, a concept known as pre-established harmony. This idea suggests that everything in the universe is interconnected, despite the absence of direct causal relationships between monads.