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 civilization, 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