Preliminary reminder The deduction of the categories is connected with so many difficulties, and necessitates such deep penetration into the primary grounds of the possibility of our cognition in general, that in order to avoid the long windedness of a complete theory and nevertheless not to omit anything in such a necessary inquiry, I have found it more advisable to prepare than to instruct the reader in the following four numbers, and only then to represent the exposition of these elements of the understanding sys tematically in the immediately following third section.a For this reason the reader should until then not be deterred by the obscurity that is ini tially unavoidable in a path that is thus far entirely unexplored, but which will, as I hope, be completely illuminated in that section.