matter

We start by explaining the nature of theory-building. Roughly, a "theory" is an organization of our thoughts on accumulated data on some domain of (human) experience. We shall apply this consideration to the atomic theory in chemistry which arose as an explanation of the philosophical notion of "matter". We shall then explain the role that Mathematics has played in this theory-building. In turn, this raises the question about the nature of Mathematics. In the process, we attempt to offer a definition of Mathematics.