The accounts given of the metaphysical deduction by Cohen,[714] Caird,[715] Riehl,[716] and Watson[717] are vitiated by failure to remark that this latter standpoint is a late development, and is out of keeping with the rest of the deduction. Riehl’s exposition has, however, the merit of comparative consistency. He explicitly recognises the important consequence which at once follows from acceptance of this later view, namely, that it is by their implying space and time that the categories differ from the notions which determine the forms of judgment; in other words, that the _categories are actualised only as schemata_. The category of substance, for instance, differs from the merely logical notion of a propositional subject, in being the concept of that which is _always_ a subject, and _never_ a predicate; and such a conception has specific meaning for us only as the _permanent in time_. Logical subjects and predicates, quantitative relations apart, are interchangeable. The relation between them is the analytic relation of identity. The concept of subject, on the other hand, transcendentally viewed, that is, as a _category_, is the apprehension of what is _permanent_, in synthetic distinction from, and relation to, its changing attributes. In other words, the transcendental distinction between _substance_ and _accidents_ is substituted for that of _subject_ and _predicate_. Similarly the logical relation of _ground_ and _consequence_, conceived as expressive of logical identity, gives way to the synthetic temporal relation of _cause_ and _effect_. And so with all the other pure forms. As categories, they are schemata. Kant has _virtually_ recognised this by the names which he gives to the categories of relation. But the proper recognition of the necessary interdependence of the intuitional and conceptual forms came too late to prevent him from distinguishing between categories and schemata, and so from creating for himself the artificial difficulties of the section on schematism. In A 82 Kant states that he intentionally omits definitions of the categories. He had good reason for so doing. The attempt would have landed him in manifold difficulties, since his views were not yet sufficiently ripe to allow of his perceiving the way of escape. In A 241 (omitted in second edition) Kant makes, however, the directly counter statement that definition of the categories is not possible, giving as his reason that, in isolation from the conditions of sensibility, they are merely logical functions, “without the slightest indication as to how they can possess meaning and objective validity.”[718]