He knew that only his scientific brethren could gauge the advance in knowledge, and consequent power over disease, due to his patient toil; it was a question of minute discoveries, of investigations unintelligible to the layman.

Some of his colleagues held that he foolishly restricted himself in declining to experimentalise _in corpore vili_, whenever such experiments were attended with pain; he was spoken of in some quarters as a "sentimentalist," a man who might go far but for his "fads." One great pathologist held that the whole idea of pursuing science for mitigation of human ills was nothing but a sentimentality and a fad.

A debate between this personage and Dr.
Derwent was brought to a close by the latter's inextinguishable mirth.
He was, indeed, a man who laughed heartily, and laughter often served him where another would have waxed choleric.
"Only a dog!" he exclaimed once to Irene, apropos of this subject, and being in his graver mood.

"Why, what assurance have I that any given man is of more importance to the world than any given dog?
How can I know what is important and what is not, when it comes to the ultimate mystery of life?
Create me a dog--just a poor little mongrel puppy--and you shall torture him; then, and not till then.

And in that event I reserve my opinion of the----" He checked himself on the point of a remark which seemed of too wide bearing for the girl's ears.