This conclusion, which appears to me unavoidably implicated in the spiritualistic hypothesis, is not merely improbable _per se_, but admits of being shown virtually impossible if we proceed to consider the consequences to which it necessarily leads. A sportsman, for example, pulls the trigger of a gun, thereby initiating a long train of physical causes, which we may take up at the point where the powder is discharged, the shot propelled, and the bird dropped. Here the man's volition is supposed to have broken in upon the otherwise continuous stream of physical causes--first by modifying the molecular movements of his brain, so as to produce the particular co-ordination of neuro-muscular movement required to take accurate aim and to fire at the right moment; next by converting a quantity of gunpowder into gas, propelling a quantity of lead through the air; and finally, by killing a bird. Now, without tracing the matter further than this, let us consider how enormous a change the will of the man has introduced, even by so trivial an exercise of its activity. No doubt the first change in the material world was exceedingly slight: the molecular movement in the cortex of his brain was probably not more than might be dynamically represented by some small fraction of a foot-pound. But so intricate is the _nexus_ of physical causality throughout the whole domain of Nature, that the intervention of even so minute a disturbance _ab extra_ is obviously bound to continue to assert an influence of ever-widening extent as well as of everlasting duration. The heat generated by the explosion of the powder, the changed disposition of the shot, the death of the bird--leading to innumerable physical changes as to stoppage of many mechanical processes previously going on in the bird's body, loss of animal heat, &c., and also to innumerable vital changes, leading to a stoppage of all the mechanical changes which the bird would have helped to condition had it lived to die some other death, to propagate its kind, and thus indirectly condition an incalculable number of future changes that would have been brought about by the ever increasing number of its descendants--these and an indefinite number of other physical changes must all be held to have followed as a direct consequence of the man's volition thus suddenly breaking in as an independent cause upon the otherwise uniform course of Nature. Now, I say that, apart from some system of pre-established harmony, it appears simply inconceivable that the order of Nature could be maintained at all, if it were thus liable to be interfered with at any moment in any number of points. And if the spiritualist takes refuge in the further hypothesis of a pre-established harmony between acts of human (not to add brute) volition and causes of a natural kind, we have only to observe that he thus lands himself in a speculative position which is practically identical with that occupied by the materialist.