metaphysics
noun
°The branch of philosophy which studies fundamental principles intended to describe or explain all that is, and which are not themselves explained by anything more fundamental; the study of first principles; the study of being insofar as it is being (ens in quantum ens).
"Philosophers sometimes say that metaphysics is the study of the ultimate nature of the universe."
°The view or theory of a particular philosopher or school of thinkers concerning the first principles which describe or explain all that is.
"The metaphysics of Thomas Aquinas holds that all real beings have both essence and existence."