substance necessarily implies the idea of unity. No one thinks that two stones very far apart form a single substance. If now we imagine them joined and soldered together, will this juxtaposition change the nature of things? Of course not; there will always be two stones and not a single one. If now we imagine them attached by an irresistible force, the impossibility of separating them will not prevent the mind from distinguishing them and will not prevent their remaining two and not one. In a word every compound is no more a single substance than is a pile of sand or a sack of wheat. We might as well say that the employees of the India Company formed a single substance.[1] It is evident therefore that a compound is never a substance and in order to find the real substance we must attain unity or the indivisible. To say that there are no such unities is to say that matter has no elements, in other words that it is not made up of substance but it is a pure phenomenon like the rainbow. The conclusion is then either that matter has no substantial reality or else it must be admitted that it is reducible to simple and consequently unextended elements, called monads.
5. Leibniz brings forward another argument in behalf of his theory of monads. This is that the essence of every substance is in force, which fact is as true of the soul as of the body. It can be proved a priori. Is it not evident that a being really exists only in so far as it acts? A being absolutely passive would be a pure nothing, and would involve a contradiction; or, by hypothesis, receiving everything from outside and having nothing through itself, it would have no characteristic, no attribute and hence would be a pure nothing. The mere fact of existence, therefore, already supposes a certain force and a certain energy.
Leibniz presses this thought of the activity of substances so far that he even admits no degree of passivity. According to
- ↑ "If the parts which act together for a common purpose, more properly compose a substance than do those which are in contact, then all the officials of the India Company would much better constitute a real substance than would a pile of stones. What else, however, is a common purpose rather than a resemblance or indeed an orderliness which our minds notice in different things? If on the other hand the unity by contact be made the basis, other difficulties arise. The parts of solid bodies are united perhaps only by the pressure of surrounding bodies, while in themselves and in their substance there is no more union than in a heap of sand, arena sine calce. Why do many rings when interlaced to form a chain compose a veritable substance rather than when there are openings so that they can be taken apart? … They are all fictions of the mind." (Letter to Arnauld).
