This article delves into the mature philosophy of Leibniz, exploring his concepts of life and organism. It aims to establish links between the scientific discoveries of the 17th century and Leibnizian metaphysical assumptions. The paper also highlights how reflections on the Cudworthian system helped the Leipzig philosopher develop his «metaphysics of the organics». The article begins with a brief overview of the querelle sur les natures plastiques to deepen some Leibnizian positions on these topics. It emphasizes Leibniz’s focus on the (...) concept of organism and its fundamental relation and difference with the concept of life. The article also addresses the notion of «nested individuality» and plural individuality in the philosopher’s writings, attempting to determine if such concepts exist. The solution to the coexistence of plural organisms within an organism provided here is mereological. Lastly, the article gathers current research results to demonstrate how the «organism» in the Leibnizian system of maturity is like a fold, leading readers toward different aspects of his metaphysics. (shrink)