§ 24. We have learnt from the great Kant that time, space, and causality, with their entire constitution, and the possibility of all their forms, are present in our consciousness quite independently of the objects which appear in them, and which constitute their content; or, in other words, they can be arrived at just as well if we start from the subject as if we start from the object. Therefore, with equal accuracy, we may call them either forms of intuition or perception of the subject, or qualities of the object _as object_ (with Kant, phenomenon), _i.e._, _idea_. We may also regard these forms as the irreducible boundary between object and subject. All objects must therefore exist in them, yet the subject, independently of the phenomenal object, possesses and surveys them completely. But if the objects appearing in these forms are not to be empty phantoms, but are to have a meaning, they must refer to something, must be the expression of something which is not, like themselves, object, idea, a merely relative existence for a subject, but which exists without such dependence upon something which stands over against it as a condition of its being, and independent of the forms of such a thing, _i.e._, _is not idea_, but a _thing-in-itself_. Consequently it may at least be asked: Are these ideas, these objects, something more than or apart from the fact that they are ideas, objects of the subject? And what would they be in this sense? What is that other side of them which is _toto genere_ different from idea? What is the thing-in-itself? _The will_, we have answered, but for the present I set that answer aside.