 The idea of the outer or relative purposiveness of one natural thing for another, which is made possible by the idea of a natural purpose, in turn makes possible the idea of nature as a system of purposes, where everything in nature is teleologically connected to everything else through relations of outer purposiveness. Kant puts this by saying that the concept of a natural purpose “necessarily leads to the idea of all of nature as a system in accordance with the rule of purposes” (§67, 379), but he also puts the point more weakly by saying that the step from the idea of a natural purpose to that of nature as a whole as a system of purposes is one which we “may” [dürfen] make (§67, 380). This does not mean that we are entitled, still less required, to ascribe an intentional cause to purposive arrangements in nature, but it does allow us to think of them as standing not only in a mechanical, but also in a teleological order. The thought of such a teleological order in turn leads to two further ideas: the idea of the ultimate purpose [letzter Zweck] of nature, which is something within nature for whose sake all other things within nature exist (§82, 426ff), and the idea of the final purpose [Endzweck] of nature, which is something outside of nature for whose sake nature as a whole exists (§67, 378f.; §84, 434ff.). While experience does not allow us to identify either nature’s ultimate purpose or its final purpose, Kant argues on a priori grounds that the final purpose of nature can only be man considered as a moral subject, that is, considered as having the supersensible ability to choose purposes freely (§84, 435). To consider man in this way is to conceive him as noumenon, rather than as part of nature. But human beings are capable of realizing their noumenal freedom only in virtue of their capacity, as natural beings, to set themselves purposes and to use nature to fulfil them. Kant calls the development of this capacity “culture”, and takes it to require the acquisition both of specific abilities (“culture of skill”) and of the ability to make choices without being influenced by the inclinations to enjoyment stemming from our animal nature (“culture of discipline”). Culture is the ultimate purpose of nature because it prepares man for what he must do in order to be the final purpose of nature (§83, 431).