their general sufficiency—­a task from which the numerous advocates and acceptors of evolution on the general concurrence of probabilities and its usefulness as a working hypothesis (with or without much conception of the manner how) are happily free.  Having hit upon a modus operandi which all who understand it admit will explain something, and many that it will explain very much, it is to be expected that Mr. Darwin will make the most of it.  Doubtless he is far from pretending to know all the causes and operations at work; he has already added some and restricted the range of others; he probably looks for additions to their number and new illustrations of their efficiency; but he is bound to expect them all to fall within the category of what he calls natural selection (a most expansible principle), or to be congruous with it—­that is, that they shall be natural causes.  Also—­and this is the critical point—­he is bound to maintain their sufficiency without intervention.

Here, at length, we reach the essential difference between Darwin, as we understand him, and Dr. Hodge.  The terms which Darwin sometimes uses, and doubtless some of the ideas they represent, are not such as we should adopt or like to defend; and we may say once for all—­aside though it be from the present issue—­that, in our opinion, the adequacy of the assigned causes to the explanation of the phenomena has not been made out.  But we do not understand him to deny “purpose, intention, or the cooperation of God” in Nature.  This would be as gratuitous as unphilosophical, not to say unscientific.  When he speaks of this or that particular or phase in the course of events or the procession of organic forms as not intended, he seems to mean not specially and disjunctively intended and not brought about by intervention.  Purpose in the whole, as we suppose, is not denied but implied.  And when one considers how, under whatever view of the case, the designed and the contingent lie inextricably commingled in this world of ours, past man’s disentanglement, and into what metaphysical dilemmas the attempt at unraveling them leads, we cannot greatly blame the naturalist for relegating such problems to the philosopher and the theologian.  If charitable, these will place the most favorable construction upon attempts to extend and unify the operation of known secondary causes, this being the proper business of the naturalist and physicist; if wise, they will be careful not to predicate or suggest the absence of intention from what comes about by degrees through the continuous operation of physical causes, even in the organic world, lest, in their endeavor to retain a probable excess of supernaturalism in that realm of Nature, they cut away the grounds for recognizing it at all in inorganic Nature, and so fall into the same condemnation that some of them award to the Darwinian.