Are you in a universe which is ruled by natural laws and, therefore, is stable, firm, absolute—and knowable? Or are you in an incomprehensible chaos, a realm of inexplicable miracles, an unpredictable, unknowable flux, which your mind is impotent to grasp? Are the things you see around you real—or are they only an illusion? Do they exist independent of any observer—or are they created by the observer? Are they the object or the subject of man’s consciousness? Are they what they are—or can they be changed by a mere act of your consciousness, such as a wish?
The nature of your actions—and of your ambition—will be different, according to which set of answers you come to accept. These answers are the province of metaphysics—the study of existence as such or, in Aristotle’s words, of “being qua being”—the basic branch of philosophy.
The branch of philosophy that studies existence is metaphysics. Metaphysics identifies the nature of the universe as a whole. It tells men what kind of world they live in, and whether there is a supernatural dimension beyond it. It tells men whether they live in a world of solid entities, natural laws, absolute facts, or in a world of illusory fragments, unpredictable miracles, and ceaseless flux. It tells men whether the things they perceive by their senses and mind form a comprehensible reality, with which they can deal, or some kind of unreal appearance, which leaves them staring and helpless.