It is a time-honored piece of theoretical speculation that nature is a kosmos, i.e. an ordered, perhaps even purposeful whole. Kant may be taken as a typical exponent of this view under conditions of modern science: he defines nature in the material sense as the total set of potential contents of our experiences and, at the same time, attempts to show that this set is subject to pervasive laws which express nature in the formal sense of the term, i.e. the internal unitary principle (or set of principles) underlying the existence of the experiential world (Kant 1781/87, A 216/B 263; 1785, §§15–16; 1786, Preface).