 A second component in the package supplies the thin concept with substantial content that confers on it explanatory power. According to Aristotle, natural entities are those that contain in themselves the principle of their own production or development, in the way that acorns contain a blueprint for their own realisation as oak trees (Physics 192b; Metaphysics 1014b). The “nature” of natural entities thus conceptualised is a subset of the features that make up their nature in the first sense. The human specification of this explanatory concept of nature aims to pick out human features that similarly function as blueprints for something like a fully realised form. According to Aristotle, for all animals that blueprint is “the soul”, that is, the integrated functional capacities that characterise the fully developed entity. The blueprint is realised when matter, i.e., the body, has attained the level of organisation required to instantiate the animal’s living functions (Charles 2000: 320ff.; Lennox 2009: 356).