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.

Religion, on the other hand, is a department of thought having no less exclusive reference to the Ultimate.  More particularly, it is a department of thought having for its object a self-conscious and intelligent Being, which it regards as a Personal God, and the fountain-head of all causation.  I am, of course, aware that the term Religion has been of late years frequently used in senses which this definition would not cover; but I conceive that this only shows how frequently the term in question has been abused.  To call any theory of things a Religion which does not present any belief in any form of Deity, is to apply the word to the very opposite of that which it has hitherto been used to denote.  To speak of the Religion of the Unknowable, the Religion of Cosmism, the Religion of Humanity, and so forth, where the personality of the First Cause is not recognized, is as unmeaning as it would be to speak of the love of a triangle, or the rationality of the equator.  That is to say, if any meaning is to be extracted from the terms at all, it is only to be so by using them in some metaphorical sense.  We may, for instance, say that there is such a thing as a Religion of Humanity, because we may begin by deifying Humanity in our own estimation, and then go on to worship our ideal.