Finding the Controlling Principles in a Philosophical Book

The reading of philosophical works has special aspects that relate to the difference between philosophy and science. We are here considering only theoretical works in philosophy, such as metaphysical treatises or books about the philosophy of nature. If a philosopher is inconsistent, you have to decide which of two sets of propositions he really means. No general knowledge isexpressible except in abstract terms. The words abstract and concrete seem to trouble many persons.