On any logical theory of Theism there can be no such distinction between ‘natural’ and ‘supernatural’ as is usually drawn, since on that theory all causation is but the action of the Divine Will.  And if we draw any distinction between such action as ‘immediate’ or ‘mediate,’ we can only mean this as valid in relation to mankind—­i.e. in relation to our experience.  For, obviously, it would be wholly incompatible with pure agnosticism to suppose that we are capable of drawing any such distinction in relation to the Divine activity itself.  Even apart from the theory of Theism, pure agnosticism must take it that the real distinction is not between natural and supernatural, but between the explicable and the inexplicable—­meaning by those terms that which is and that which is not accountable by such causes as fall within the range of human observation.  Or, in other words, the distinction is really between the observable and the unobservable causal processes of the universe.

Although science is essentially engaged in explaining, her work is necessarily confined to the sphere of natural causation; beyond that sphere (i.e. the sensuous) she can explain nothing.  In other words, even if she were able to explain the natural causation of everything, she would be unable to assign the ultimate raison d’etre of anything.

It is not my intention to write an essay on the nature of causality, or even to attempt a survey of the sundry theories which have been propounded on this subject by philosophers.  Indeed, to attempt this would be little less than to write a history of philosophy itself.  Nevertheless it is necessary for my purpose to make a few remarks touching the main branches of thought upon the matter[50].

The remarkable nature of the facts. These are remarkable, since they are common to all human experience.  Everything that happens has a cause.  The same happening has always the same cause—­or the same consequent the same antecedent.  It is only familiarity with this great fact that prevents universal wonder at it, for, notwithstanding all the theories upon it, no one has ever really shown why it is so.  That the same causes always produce the same effects is a proposition which expresses a fundamental fact of our knowledge, but the knowledge of this fact is purely empirical; we can show no reason why it should be a fact.  Doubtless, if it were not a fact, there could be no so-called ’Order of Nature,’ and consequently no science, no philosophy, or perhaps (if the irregularity were sufficiently frequent) no possibility of human experience.  But although this is easy enough to show, it in no wise tends to show why the same causes should always produce the same effects.

So manifest is it that our knowledge of the fact in question is only empirical, that some of our ablest thinkers, such as Hume and Mill, have failed to perceive even so much as the intellectual necessity of looking beyond our empirical knowledge of the fact to gain any explanation of the fact itself.  Therefore they give to the world the wholly vacuous, or merely tautological theory of causation—­viz. that of constancy of sequence within human observation[51].