As yet, the ultimates of all things lie hidden in the womb of the vast unknown.

But just as in the case of a man we can tell what organs are vital, though we are ignorant what the vital spark may be, so in our great cosmical laws we can say in what their power resides, though we know not really what they are.

Whether mind be but a sublimated form of matter, or, what amounts to the same thing, matter a menial kind of mind, or whether, which seems less likely, it be a something incomparable with substance, of one thing we are sure, the same laws of heredity govern both.

In each a like chain of continuity leads from the present to the dim past, a connecting clue which we can follow backward in imagination.

Now what spontaneous variation is to the material organism, imagination, apparently, is to the mental one.