The problem of the unity and the plurality is one of the oldest historically, and it inevitably arises from our attempts to think in a consistent way about the Physical Reality.
On the one hand, our experience, which is piecemeal and fragmentary, seems to reveal an indefinite plurality of parts and constituents. And this is how it appeared to Democritus and Newton.
On the other hand, there are compelling reasons for regarding the physical world as a single unity. And, today, the modern science looks upon nature as a realm of inter-connected events where nothing is ultimately entirely independent.