In short, our whole key of thinking or tone of thought having been in certain respects changed, we can no longer anticipate that in these respects it should continue to harmonize with the unalterable system of theology. Such I conceive to be the ways in which Science has exerted her influence upon Religion, and it is needless to dwell upon the potency of their united effect. No one can read even a newspaper without perceiving how great this effect has been. On the one hand, sceptics are triumphantly confident that the light of dawning knowledge has begun finally to dispel the darkness of superstition, while religious persons, on the other hand, tremble to think what the future, if judged by the past, is likely to bring forth. On both sides we have free discussion, strong language, and earnest canvassing. Year by year stock is taken, and year by year the balance is found to preponderate in favour of Science. This being the state of things of the present time, I think that with the experience of the kind and degree of influence which Science has exerted upon Religion in the past, we have material enough whereby to estimate the probable extent of such influence in the future. This, therefore, I shall endeavour to do by seeking to define, on general principles, the limits within which it is antecedently possible that the influence in question can be exercised. But in order to do this, it is necessary to begin by estimating the kind and degree of the influence which has been exerted by Science upon Religion in the past. Thus much premised, we have in the first place to define the essential nature both of Science and of Religion: for this is clearly the first step in an analysis which has for its object an estimation of the actual and possible effects of one of these departments of thought upon the other. Science, then, is essentially a department of thought having exclusive reference to the Proximate. More particularly, it is a department of thought having for its object the explanation of natural phenomena by the discovery of natural (or proximate) causes. In so far as Science ventures to trespass beyond this her only legitimate domain, and seeks to interpret natural phenomena by the immediate agency of supernatural or ultimate causes, in that degree has she ceased to be physical science, and become ontological speculation. The truth of this statement has now been practically recognized by all scientific workers; and terms describing final causes have been banished from their vocabulary in astronomy, chemistry, geology, biology, and even in psychology.