Meaning: This quote is attributed to the German philosopher and mathematician Gottfried Wilhelm Leibniz, who lived in the 17th and 18th centuries. The quote reflects Leibniz's metaphysical views, particularly his concept of monads and their inherent nature. In order to understand the quote, it is necessary to delve into Leibniz's philosophy, particularly his theory of monads and his concept of pre-established harmony.

In Leibniz's metaphysical system, a monad is an indivisible, immaterial, and autonomous entity that represents the basic building block of the universe. Monads are characterized by their perception and appetition, which can be roughly translated as "consciousness" and "striving" respectively. According to Leibniz, each monad reflects the entire universe from its own unique perspective, and its internal states are the result of its perceptions and appetitions.

The quote emphasizes the idea that the natural changes of monads arise from an internal principle rather than from external causes. This reflects Leibniz's view that monads are self-contained and self-sufficient entities that do not interact with each other through external influences. Instead, the changes that occur within monads are the result of their internal nature and the unfolding of their inherent perceptions and appetitions.

Leibniz's rejection of external causes influencing the inner being of monads is a key aspect of his philosophy. He argued that the monads are "windowless" entities, meaning that they do not have any direct causal interaction with each other. Instead, each monad represents a microcosm that reflects the entire universe from its own unique perspective. As a result, the changes and developments within a monad are the result of its internal nature and its internal principles of perception and appetition.

Leibniz's concept of pre-established harmony further elucidates his position on the internal nature of monads. According to Leibniz, the universe is a harmonious system in which the internal states of individual monads are coordinated with each other in a pre-established manner. This means that while monads do not causally interact with each other, their internal states unfold in a way that is in harmony with the internal states of all other monads, reflecting a pre-established plan or divine order.

The concept of pre-established harmony serves to reinforce Leibniz's view that the changes within monads arise from their internal principles rather than from external causes. It suggests that the natural development of each monad is inherently linked to the overall harmony of the universe, and that this harmony is not disrupted by external influences.

In summary, Leibniz's quote reflects his belief in the internal nature of monads and their self-contained existence. According to Leibniz, the natural changes of monads arise from their internal principles of perception and appetition, rather than from external influences. This perspective is rooted in his broader metaphysical framework, which emphasizes the self-sufficiency of monads and the pre-established harmony of the universe.