The basis of any knowledge is a set of axioms, i.e. irreducible facts underlying everything in the scope of the field of study, underlying any observation, derivation, proof, etc. The axioms of reality are facts underlying everything in the scope of reality. Metaphysics is the study of these axioms and their implications, i.e. it is the study of the nature of reality as a whole. Metaphysics is fundamental to all thought and action; its truths — grasped implicitly or explicitly — are presupposed in any conscious thought or action, because one’s basic view of reality is what guides one’s basic approach to dealing with it.