Chapter VI.
The third class of objects for the subject is constituted by the formal element in perception, the forms of outer and inner sense, space and time. This class of ideas, in which time and space appear as pure intuitions, is distinguished from that other class in which they are objects of perception by the presence of matter which has been shown to be the perceptibility of time and space in one aspect, and causality which has become objective, in another. Space and time have this property, that all their parts stand to one another in a relation in which each is determined and conditioned by another. This relation is peculiar, and is intelligible to us neither through understanding nor through reason, but solely through pure intuition or perception a priori. And the law according to which the parts of space and time thus determine one another is called the law of sufficient reason of being. In space every position is determined with reference to every other position, so that the first stands to the second in the relation of a consequence to its ground. In time every moment is conditioned by that which precedes it. The ground of being, in the form of the law of sequence, is here very simple owing to the circumstance that time has only one dimension. On the nexus [pg 485] of the position of the parts of space depends the entire science of geometry. Ground of knowledge produces conviction only, as distinguished from insight into the ground of being. Thus it is that the attempt, which even Euclid at times makes, to produce conviction, as distinguished from insight into the ground of being, in geometry, is a mistake, and induces aversions to mathematics in many an admirable mind.