theoretical or practical data, in all cases by means of a corresponding intuition) are things of fact (res facti). Of this kind are the mathematical properties of magnitudes (in geometry), because they are susceptible of a presentation a priori for the theoretical use of Reason.

Further, things or their characteristics, which can be exhibited in experience (either our own or that of others through the medium of testimony) are likewise things of fact. — And, what is very remarkable, there is one rational Idea (susceptible in itself of no presentation in intuition, and consequently, of no theoretical proof of its possibility) which also comes under things of fact. This is th