Metaphysics has been given many definitions over the years, Aristotle says that it is the science of being as being, or the study of everything that can be. Another definition given to metaphysics is the science of the most universal conceptions. My personal favorite would be metaphysics is the science of the most abstract conceptions.
This, to me, is saying that metaphysics is the study of ideas real physics does not solve, things that cannot be measured by a gauge. Aristotle also said “The first science deals with things which are both separate (from matter) and unmovable.” The study of things not made from any physical material, and cannot be removed from human life, such as: the human soul, or the existence of god. You can’t touch, see, taste, smell, or hear these things; they exist only in the state of mind.
There are three key ideas to metaphysics: being, substance, and cause. The most important thing about the idea of being is that it cannot be defined. If it were given a definition “by proximate genus and ultimate difference”, the word itself, being, includes anything that ever was, and everything that ever will, so it cannot exclude anything, and therefore cannot be included in a genus or group. With this definition of being, it cannot be argued, “that any lower concepts will have a greater comprehension than being.”
There could not be anything added to being, if being includes everything, so the equation “Substance = Being + a” is incorrect. It could be said that one can use metaphysics to have a better understanding of religion, I know the bible seems kind of abstract to me.