osites would be a task which hardly any
sane man would undertake. It would imply a claim to be able to rise at
once above both, and see the truth which included all that both could
teach. But it is a very useful undertaking, and not beyond the reach of
thoughtful inquiry by an ordinary man, to examine the relations between
the two, and thus to help not a few to find a way for themselves out of
the perplexity. And this inquiry may well begin by asking what is the
origin and nature of scientific belief on the one hand and of religious
belief on the other. In this Lecture I propose to deal with the former.

It is not necessary to include in the Science of which I am to speak
either Mathematics or Metaphysics. In as far as I need touch on what
belongs to either, it will be only for the purpose of answering
objections or of excluding what is irrelevant. And the consequent
restriction of our consideration to the Science which concerns itself
with Nature greatly simplifies the task that I have undertaken. For it
will be at once admitted in the present day by all but a very few that
the source of all scientific knowledge of this kind is to be found in
the observations of the senses, including under that word both the
bodily senses which tell us all we know of things external, and that
internal sense by which we know all or nearly all that takes place
within the mind itself. And so also will it be admitted that the Supreme
Postulate, without which scientific knowledge is impossible, is the
Uniformity of Nature.

Science lays claim to no revelations. No voice of authority declares
what substances there are in the world, what are the properties of those
substances, what are the effects and operations of those properties. No
traditions handed down from past ages can do anything more than transmit
to us observations made in those times, which, so far as we can trust
them, we may add to the observations made in our own times. The
materials in short which Science has to handle are obtained by
experience.

But on the other hand Science can deal with these materials only on the
condition that they are reducible to invariable laws. If any observation
made by the senses is not capable of being brought under the laws which
are found to govern all other observations, it is not yet brought under
the dominion of Science. It is not yet explained, nor understood. As far
as Science is concerned, it may be called as yet non-existent. It is for