appears along with space and time as the third pure form, and therefore as dependent on our intellect. This table contains all the fundamental truths which are rooted in our perceptive or intuitive knowledge _a priori_, expressed as first principles independent of each other. What is special, however, what forms the content of arithmetic and geometry, is not given here, nor yet what only results from the union and application of those formal principles of knowledge. This is the subject of the “Metaphysical First Principles of Natural Science” expounded by Kant, to which this table in some measure forms the propædutic and introduction, and with which it therefore stands in direct connection. In this table I have primarily had in view the very remarkable _parallelism_ of those _a priori_ principles of knowledge which form the framework of all experience, but specially also the fact that, as I have explained in § 4 of the first volume, matter (and also causality) is to be regarded as a combination, or if it is preferred, an amalgamation, of space and time. In agreement with this, we find that what geometry is for the pure perception or intuition of space, and arithmetic for that of time, Kant’s _phoronomy_ is for the pure perception or intuition of the two _united_. For matter is primarily that which is movable in space. The mathematical point cannot even be conceived as movable, as Aristotle has shown (“Physics,” vi. 10). This philosopher also himself provided the first example of such a science, for in the fifth and sixth books of his “Physics” he determined _a priori_ the laws of rest and motion.