 Kant is concerned with the role of teleology in our understanding not only of individual organisms, but also of other natural things and processes, and of nature as a whole. Experience presents us with many cases in which features of a living thing’s environment, both organic and inorganic, are beneficial or indeed necessary to it: for example rivers are helpful to the growth of plants, and thus indirectly to human beings, because they deposit soil and thus create fertile land (§63, 367); grass is necessary for cattle and other herbivorous animals, which in turn provide food for carnivores (§63, 368). Kant makes the negative point (a version of which he had earlier argued at length in the Only Possible Argument for the Existence of God of 1763) that we can understand these arrangements without appeal to purposes. We can account for the origin of rivers mechanically, and even though grass must be regarded as an purpose on account of its internal organization, we do not need to appeal to its usefulness to other living things in order to comprehend it. However, he does hold that the natural objects figuring in these useful arrangements have a type of purposiveness, namely outer or relative purposiveness. They can be counted as purposive in this relative sense as long as the thing to whose existence they contribute is a living thing, and hence has inner purposiveness (this condition is stated most clearly at §82, 425).