Why may not Man be the _nexus_ between a world of "matter" and a world of "spirits,"-- Man, who is equally connected with the material world by his body, and with the spiritual by his soul,--who is, as it were, "mind incarnate," spirit in flesh?
And why may there not be higher spirits still, whether embodied in subtler and more refined vehicles, or existing apart from all material forms, in those other worlds which Astronomy has brought to light?
No reason can be assigned for a negative answer to these and similar queries, unless it be that _we cannot conceive of pure spirit without bodily form_; and this may be true, if it be meant merely to affirm that we can find no sensible image for it, nothing by which it can be represented to our sight, or pictured in our imagination, as visible things may be; but it is not true, if it be meant to imply that we have no distinct notion of "mind" or "spirit," for it is as clearly known by its properties, of thought, feeling, volition, and consciousness, as matter itself can be; and who will venture to define, or to depict, or to form any image of _the substance of matter_, apart from the properties which belong to it?
We are under no necessity, then, of adopting the theory of "unisubstancisme," and we cannot found upon it in argument without building on a mere gratuitous assumption.
IV.

Our _fourth_ proposition is, That the same reason which warrants us in ascribing certain properties and phenomena to a distinct substance called "matter," equally warrants us in ascribing certain other properties and phenomena to a distinct substance called "mind;" and that the difference between their respective properties and phenomena is so great as to justify the belief that the _substances_ are different and ought to be denominated by distinctive names.
When Materialists affirm, as they do, the existence of one only substantive being in Nature, and represent all our mental phenomena as the mere results of physical organization, they assume that "matter," at least, is a real _entity_; that it is a _substance_ or _substratum_ in which certain powers or qualities inhere; and that its existence, as such, is evident and undeniable.

We are entirely relieved, therefore, by their own admission or assumption, from the necessity of discussing the more general problem of Ontology; the problem, whether we can prove the existence of _any_ being, properly so called, from a mere series of phenomena, a succession of appearances.

They virtually admit, since they evidently assume, that the phenomena must have a substance under them, the qualities a substratum in which they inhere.

Now, the very same reason which warrants, or rather obliges them to recognize "matter" as a substance and not as a shadow,--as an _entity_ which really exists and manifests itself by its properties and effects,--must equally warrant, or rather oblige them to recognize "mind" or "spirit" also as a distinct substantive being, unless it can be shown either that its properties are the same with those of matter, or that they may be accounted for by some peculiar modification of matter, some law of physical organization.