I've been gradually moving through the branches of philosophy and showing how Scientology encompasses each. Now we come to metaphysics. This is probably the most difficult branch of philosophy to define. Wikipedia gives a long definition while Webster's 1828 dictionary gives a simpler one.
Originally metaphysics was used to describe the books (and hence the subjects in those books) by Aristotle that came after (meta) his books about physics. Metaphysics has expanded over the centuries to include anything that doesn't fit into the rest of philosophy, so in a way it still lives up to its original definition although it could now be called meta-philosophy. To keep it simple, or as simple as I can, I'll define it like this: it covers the basic concepts of what underlies existence. Concepts such as being, existence, causation, space, time, knowledge, mind, spirit and many more fall into metaphysics. Unfortunately the more you dig into what it means the more complicated and convoluted it becomes. So I'll stop there.
Scientology covers the area of metaphysics in its usual practical way. The Prelogics are probably the first summation of L. Ron Hubbard's discoveries in this area, defining the common denominator of all life impulses and how universes are created. Next came the Factors which cover being, existence, causation and much more. Finally the Scientology Axioms sum up everything (literally).
These fundamentals are given very concisely and when you first read them may be too concentrated to easily digest, so in the next couple of days I'll give you examples of how they can be used in life.