According to Kant, the categorical imperative is possible because, whilst we can be thought of as members of both of these worlds (understanding and appearance), it is the world of understanding that “contains the ground of the world of sense and so too of its laws.” What this means is that the world of understanding is more fundamental than, or ‘grounds’, the world of sense. Because of this, the moral law, which clearly applies to the world of understanding, also applies to the world of sense as well, because the world of understanding has priority. To put the point slightly differently: Because the world of understanding is more fundamental and primary, its laws hold for the world of sense too. So the moral law binds us even in the world of appearances.