In his Monadology, the philosopher Leibniz proposes a theory of pre-established harmony (sometimes called the concomitance hypothesis) in order to understand how things are connected in the world.
God, creator of universal harmony between the monads
According to Leibniz, each monad is like a clock, it behaves independently of the other monads. However, each monad is synchronized with another by God according to his conception of the perfect universe. In accordance with his pre-established theory of harmony, Leibniz argues that the monads are unrelated to each other, with each monad alone expressing the entire universe.