One of Leibniz’s most original ideas is his conception of the living individual as a hierarchical network of living beings whose relationships are essential to the proper functioning of its organic body. This idea is also valid to explain any existing order in nature that depends on the set of relationships of living beings that inhabit it. Both ideas are present in the conception of the natural world that Leibniz presents in his Monadology through his idea of biological infinitism. According (...) to this idea, nature consists of infinite theatres where living beings unfold their vital functions. Through this idea Leibniz defines both the biological complexity of nature and the living individual, which is in turn a portion of nature that unfolds from an infinite set of inferior living beings. The thesis that I defend in this work is that this Leibnizian understanding of the living individual and the natural complexity that includes infinite hierarchical levels of individuality has a marked ecological sense, as we would say today. This Leibnizian metaphysics of individuality that we could call biological is also interesting in light of the recent studies in the philosophy of biology. (shrink)