Concepts, so far as they are referred to objects, independently of the possibility or impossibility of the cognition of these objects, have their field which is determined merely according to the relation that their Object has to our cognitive faculty in general. The part of this field in which knowledge is possible for us is a ground or territory (_territorium_) for these concepts and the requisite cognitive faculty. The part of this territory, where they are legislative, is the realm (_ditio_) of these concepts and of the corresponding cognitive faculties. Empirical concepts have, therefore, their territory in nature, as the complex of all objects of sense, but no realm, only a dwelling-place (_domicilium_); for though they are produced in conformity to law they are not legislative, but the rules based on them are empirical and consequently contingent. Our whole cognitive faculty has two realms, that of natural concepts and that of the concept of freedom; for through both it is legislative _a priori_. In accordance with this, Philosophy is divided into theoretical and practical. But the territory to which its realm extends and in which its legislation is _exercised_, is always only the complex of objects of all possible experience, so long as they are taken for nothing more than mere phenomena; for otherwise no legislation of the Understanding in respect of them is conceivable. Legislation through natural concepts is carried on by means of the Understanding and is theoretical. Legislation through the concept of freedom is carried on by the Reason and is merely practical. It is only in the practical [sphere] that the Reason can be legislative; in respect of theoretical cognition (of nature) it can merely (as acquainted with law by the Understanding) deduce from given laws consequences which always remain within [the limits of] nature. But on the other hand, Reason is not always therefore _legislative_, where there are practical rules, for they may be only technically practical. Understanding and Reason exercise, therefore, two distinct legislations in regard to one and the same territory of experience, without prejudice to each other. The concept of freedom as little disturbs the legislation of nature, as the natural concept influences the legislation through the former.--The possibility of at least thinking without contradiction the co-existence of both legislations, and of the corresponding faculties in the same subject, has been shown in the Critique of pure Reason; for it annulled the objections on the other side by exposing the dialectical illusion which they contain.