directed not by calculating thought, as we conceive ourselves to be, but by some motive influence, our ignorance of the nature of which we disguise from ourselves, and call it instinct, but which we believe at least to be some property residing in the organisation; and we are not to suppose that the human body, the most complex of all material structures, has slighter powers in it than the bodies of a seed, a bird, or an insect.  Let us listen to Spinoza himself:—­

“There can be no doubt,” he says, “that this hypothesis is true, but unless I can prove it from experience, men will not, I fear, be induced even to reflect upon it calmly, so persuaded are they that it is by the mind only that their bodies are set in motion.  And yet what body can or cannot do no one has yet determined; body, i.e., by the law of its own nature, and without assistance from mind.  No one has so probed the human frame as to have detected all its functions and exhausted the list of them:  and there are powers exhibited by animals far exceeding human sagacity; and again, feats are performed by somnambulists on which in the waking state the same persons would never venture —­itself a proof that body is able to accomplish what mind can only admire.  Men say that mind moves body, but how it moves it they cannot tell, or what degree of motion it can impart to it; so that, in fact, they do not know what they say, and are only confessing their own ignorance in specious language.  They will answer me, that whether or not they understand how it can be, yet that they are assured by plain experience that unless mind could perceive, body would be altogether inactive; they know that it depends on the mind whether the tongue speak or not.  But do they not equally experience that if their bodies are paralysed their minds cannot think?  That if their bodies are asleep their minds are without power?  That their minds are not at all times equally able to exert themselves even on the same subject, but depend on the state of their bodies?  And as for experience proving that the members of the body can be controlled by the mind, I fear experience proves very much the reverse.  But it is absurd, they rejoin, to attempt to explain from the mere laws of body such things as pictures, or palaces, or works of art; the body could not build a church unless mind directed it.  I have shown, however, that we do not vet know what body can or cannot do, or what would naturally follow from the structure of it; that we experience in the feats of somnambulists something which antecedently to that experience would have seemed incredible.  This fabric of the human body exceeds infinitely any contrivance of human skill, and an infinity of things, as I have already proved, ought to follow from it.”

We are not concerned to answer this reasoning, although if the matter were one the debating of which could be of any profit, it would undoubtedly have its weight, and would require to be patiently considered.  Life is too serious, however, to be wasted with impunity over speculations in which certainty is impossible, and in which we are trifling with what is inscrutable.