Sec. 13. Hence, an objector to the above syllogism need not be a materialist; it is not even necessary that he should hold any theory of things at all. Nevertheless, for the sake of definition, I shall assume that he is a materialist. As a materialist, then, he would appear to be as much entitled to his hypothesis as a theist is to his--in respect, I mean, of this particular argument. For although I think, as before shown, that in strict reasoning a theist might have taken exception to the last-quoted passage from Mill in its connection with the law of causation, that passage, if considered in the present connection, is certainly unanswerable. What is the state of the present argument as between a materialist and a theist? The mystery of existence and the inconceivability of matter thinking are their common data. Upon these data the materialist, justly arguing that he has no right to make his own conceptive faculty the unconditional test of objective possibility, is content to merge the mystery of his own mind's existence into that of Existence in general; while the theist, compelled to accept without explanation the mystery of Existence in general, nevertheless has recourse to inventing a wholly gratuitous hypothesis to explain one mode of existence in particular. If it is said that the latter hypothesis has the merit of causing the mystery of material existence and the mystery of mental existence to be united in a thinkable manner--viz., in a self-existing Mind,--I reply, It is not so; for in whatever degree it is unthinkable that Matter should be the cause of Mind, in that precise degree must it be unthinkable that Mind was ever the cause of Matter, the correlatives being in each case the same, and experience affording no evidence of causality in either.