Meaning: The quote "But in simple substances the influence of one monad over another is ideal only" is attributed to Gottfried Wilhelm Leibniz, a prominent philosopher and mathematician of the 17th century. This quote encapsulates one of the key concepts in Leibniz's philosophy, the notion of monads and their interactions.

In order to fully understand the significance of this quote, it is necessary to delve into Leibniz's philosophy and his conception of monads. Leibniz developed the concept of monads as the ultimate constituents of reality. According to him, monads are indivisible, non-material, and unextended entities that make up the fabric of the universe. Each monad is unique, and they do not interact with each other in the traditional sense. Instead, they reflect the entire universe from their own perspective, and their interactions are ideal or pre-established by a divine creator.

The term "simple substances" in the quote refers to these monads, which are the basic building blocks of all existence, according to Leibniz. Unlike material substances, which are composed of parts and can be divided into smaller components, monads are simple and cannot be broken down further. They are the ultimate metaphysical units that underlie all physical phenomena.

When Leibniz states that the influence of one monad over another is ideal only, he is emphasizing the unique nature of monadic interactions. In his philosophy, monads do not causally interact with each other in the way that material objects do. Instead, their interactions are ideal, meaning that they reflect a pre-established harmony in the universe. This pre-established harmony is a fundamental aspect of Leibniz's philosophy, and it suggests that the interactions between monads are not the result of direct influence or causation, but rather a reflection of a pre-determined order.

Leibniz's concept of monads and their ideal interactions has significant implications for his broader metaphysical and theological views. It reflects his belief in a harmonious and orderly universe, governed by a pre-established divine plan. According to Leibniz, the interactions of monads, despite being ideal, are perfectly synchronized and reflect the unity and coherence of the universe as a whole.

Furthermore, the idea of ideal interactions between monads highlights the holistic nature of Leibniz's philosophy. Each monad, as a reflection of the entire universe, contains within itself the entire causal chain of events, past, present, and future. This leads to the concept of "pre-established harmony," wherein the interactions between monads are not the result of direct influence, but rather a reflection of the underlying unity and coherence of the universe.

In conclusion, the quote "But in simple substances the influence of one monad over another is ideal only" captures one of the central tenets of Leibniz's philosophy of monads. It underscores the unique nature of monadic interactions and their ideal, pre-established harmony. Leibniz's concept of monads and their interactions provides a distinctive perspective on the nature of reality, emphasizing unity, harmony, and divine order.