s a bad one, and scepticism a sin; that when good authority
has pronounced what is to be believed, and faith has accepted it, reason
has no further duty. There are many excellent persons who yet hold by
these principles, and it is not my present business, or intention, to
discuss their views. All I wish to bring clearly before your minds is
the unquestionable fact, that the improvement of natural knowledge
is effected by methods which directly give the lie to all these
convictions, and assume the exact reverse of each to be true.

The improver of natural knowledge absolutely refuses to acknowledge
authority, as such. For him, scepticism is the highest of duties; blind
faith the one unpardonable sin. And it cannot be otherwise, for every
great advance in natural knowledge has involved the absolute rejection
of authority, the cherishing of the keenest scepticism, the annihilation
of the spirit of blind faith; and the most ardent votary of science
holds his firmest convictions, not because the men he most venerates
hold them; not because their verity is testified by portents and
wonders; but because his experience teaches him that whenever he chooses
to bring these convictions into contact with their primary source,
Nature--whenever he thinks fit to test them by appealing to experiment
and to observation--Nature will confirm them. The man of science has
learned to believe in justification, not by faith, but by verification.

Thus, without for a moment pretending to despise the practical results
of the improvement of natural knowledge, and its beneficial influence
on material civilisation, it must, I think, be admitted that the great
ideas, some of which I have indicated, and the ethical spirit which
I have endeavoured to sketch, in the few moments which remained at my
disposal, constitute the real and permanent significance of natural
knowledge.

If these ideas be destined, as I believe they are, to be more and more
firmly established as the world grows older; if that spirit be fated, as
I believe it is, to extend itself into all departments of human thought,
and to become co-extensive with the range of knowledge; if, as our race
approaches its maturity, it discovers, as I believe it will, that there
is but one kind of knowledge and but one method of acquiring it; then
we, who are still children, may justly feel it our highest duty to
recognise the advisableness of improving natural knowledge, and so to
aid ourselves and