16 REPORT—1899. 
of man’s increasing mastery over Nature, and that mastery is increasingly 
a mastery of mind ; it is an increasing power to use the forces of what 
we call inanimate nature in place of the force of his own or other creatures’ 
bodies ; it is an increasing use of mind in place of muscle. 
Ts it to be thought that that which has brought the mind so greatly 
into play has had no effect on the mind itself? Is that part of the mind 
which works out scientific truths a mere slavish machine producing results 
it knows not how, having no part in the good which in its working it 
brings forth ? 
What are the qualities, the features of that scientific mind which has 
wrought, and is working, such great changes in man’s relation to Nature ? 
In seeking an answer to this question we have not to inquire into the 
attributes of genius. Though much of the progress of science seems to 
take on the form of a series of great steps, each made by some great man, 
the distinction in science between the great discoverer and the humble 
worker is one of degree only, not of kind. As I was urging just now, the 
greatness of many great names in science is often, in large part, the great- 
ness of occasion, not of absolute power. The qualities which guide one 
man to asmall truth silently taking its place among its fellows, as these go 
to make up progress, are at bottom the same as those by which another 
man is led to something of which the whole world rings. 
The features of the fruitful scientific mind are in the main three. 
In the first place, above all other things, his nature must be one which 
vibrates in unison with that of which he is in search ; the seeker after 
truth must himself be truthful, truthful with the truthfulness of Nature. 
For the truthfulness of Nature is not wholly the same as that which man 
sometimes calls truthfulness. It is far more imperious, far more exacting. 
Man, unscientific man, is often content with ‘the nearly ’ and ‘ the almost.’ 
Nature never is. It is not her way to call the same two things which 
differ, though the difference may be measured by less than the thousandth 
of a milligramme or of a millimetre, or by any other like standard of minute- 
ness. And the man who, carrying the ways of the world into the domain 
of science, thinks that he may treat Nature’s differences in any other way 
than she treats them herself, will find that she resents his conduct ; if he in 
carelessness or in disdain overlooks the minute difference which she holds 
out to him as a signal to guide him in his search, the projecting tip, as it 
were, of some buried treasure, he is bound to go astray, and the more strenu- 
ously he struggles on, the farther will he find himself from his true goal. 
In the second place, he must be alert of mind. Nature is ever making 
signs to us, she is ever whispering to us the beginnings of her secrets ; the 
scientific man must be ever on the watch, ready at once to lay hold of 
Nature’s hint, however small, to listen to her whisper, however low. 
In the third place, scientific inquiry, though it be pre-eminently an 
intellectual effort, has need of the moral quality of courage—not so much 
the courage which helps a man to face a sudden difficulty as the courage 
