The passage quoted from the letter of 1772 to Herz may perhaps be connected with the stage revealed in the _Reflexionen_ already cited. “Comparing, combining, and separating” may be the “some few principles of the understanding” there referred to. That, however, is doubtful, for the next stage in the development likewise resulted in a threefold division. This second stage finds varied expression in _Reflexionen_, ii. 483, 522, 528, 556-63. These, in so far as they agree, distinguish three classes of categories--of thesis, of analysis, and of synthesis. The first covers the categories of quality and modality, the second those of quantity, the third those of relation. _Reflexionen_, ii. 528 is as follows: [Thesis = ] “The metaphysical concepts are, first, absolute: possibility and existence; secondly, relative: (_a_) Unity and plurality: _omnitudo_ and _particularitas_. [Analysis = ] (_b_) Limits: the first, the last: _infinitum_, _finitum_. [Anticipates the later category of limitation.] (_c_) Connection: co-ordination: whole and part [Synthesis = ] [anticipates the later category of reciprocity], simple and compound; subordination: (1) Subject and predicate. (2) Ground and consequence. This, and the connected _Reflexionen_ enumerated above, are of interest as proving that Kant’s table of categories was in all essentials complete before the idea had occurred to him of further systematising it or of guaranteeing its completeness by reference to the logical classification of the forms of judgment. They also justify us in the belief that when Kant set himself to discover such a unifying principle the above list of categories and the existing logical classifications must have mutually influenced one another, each undergoing such modification as seemed necessary to render the parallelism complete. This, as we shall find, is what actually happened. The logical table, for instance, induced Kant to distinguish the categories of quality from those of modality, while numerous changes were made in the logical table itself in order that it might yield the categories required.