Thus, even in the material world itself, we distinguish sulphur from soda, gold from granite, and magnesia from electricity or _odyle_.

Why?
Because, while they have some properties in common, in virtue of which we rank them in the same category as "material substances," they have, severally, certain distinctive or peculiar characteristics, which forbid us to call the one by the same name as the other.

And for precisely the same reason, when we find another class of properties and powers existing in certain beings, which are totally different from those belonging to mere material substances,--incapable not only of being identified with them, but also of being accounted for by means of them,--we are equally warranted in ascribing these properties to a _substance_, and in affirming that this substance, of which we know nothing except through its properties, is radically different from "matter." That there is something more than a mere _verbal_ difference between us and our opponents might seem to be admitted by themselves, when they evince so much zeal in assailing our position and defending their own; but it becomes strikingly apparent as soon as we extend our inquiry so as to embrace the grand question respecting the distinction, if any, between God and the material universe.
Some, again, who are substantially, at least in all important respects, on our side of the question, have not been satisfied with showing that the two sets of properties are generically different, and that the same reason exists for ascribing the one to a distinct substantive being called "mind," as for ascribing the other to a substantive being called "matter." They have been anxious to advance a step further; and to show that the two sets of properties are _mutually exclusive_, and that they could not possibly _coexist_ in the same subject.

This is the declared object of Baxter's Work on the Soul, which professes to prove that the only power belonging to "matter," namely, its _vis inertiae_, or resistance to any change in its present state, is inconsistent with its possession of any active power.

It is not held sufficient to show that the properties are generically different, and that the substances in which these properties inhere may and should be designated by distinct names, as matter and spirit, soul and body; but it must be further proved that they are so heterogeneous and inconsistent as to be mutually exclusive, and incapable of coexisting in the same substance.