Definition: The one and only substance, which composes existence
More about the term: The big problem for Leibniz was, mathematically, if something takes up a finite amount of space then it must be divisible. This was the infinite divisibility of matter (DM, Sec. 9, lines 6-9). Why is this a problem? Because he’s trying to solve the question, “What is substance?” Sub+stans, that which stands underneath. This is where he gets the word monad, mono-, one, unity. A monad must have these qualities:
- Cannot be divided any further
- Does not have parts
- Not material, but rather more like a soul
- According to Leibniz, they are a spritual substance
- Infinite number of them
Spinoza thought that substance entails ontological independence, i.e., the sufficient reason for the continued existence of the thing is eternal to it. Thus, there is only one substance: God. Monads are made by creation and destroyed by annihilation whereas composites are respective to the assembling of the parts and disassembling of the parts.
So, if the monads are simply substances, then what is it that we see, touch, feel, taste, and hear? It is the phenomena: the “phenomena bene fundata,” well founded phenomena. The series of each monad, i.e. how each monad ‘unfolds’ is determined by it ‘inner nature,’ inner series,’ etc. This is contingently deterministic. God is an omnipotent monad who exists within himself.