Note (return) — Chapter V

The analysis of thought clearly reveals that the mind of man is in possession of ideas, notions, beliefs, principles (as e.g., the idea of space, duration, cause, substance, unity, infinity), which are not derived from sensation and experience, and which can not be drawn out of sensation and experience by any process of generalization. These ideas have this incontestable peculiarity, as distinguished from all the phenomena of sensation, that, whilst the latter are particular, contingent, and relative, the former are universal, necessary, and absolute. As an example, and a proof of the reality and validity of this distinction, take the ideas of body and of space, the former unquestionably derived from experience, the latter supplied by reason alone. "I ask you, can not you conceive this book to be destroyed? Without doubt you can. And can not you conceive the whole world to be destroyed, and no matter whatever in existence? You can. For you, constituted as you are, the supposition of the non-existence of bodies implies no contradiction. And what do we call the idea of a thing which we can conceive of as non-existing? We call it a contingent and relative idea. But if you can conceive this book to be destroyed, all bodies destroyed, can you suppose space to be destroyed? You can not. It is in the power of man's thought to conceive the non-existence of bodies; it is not in the power of man's thought to conceive the non-existence of space. The idea of space is thus a necessary and absolute idea." 224