In the north of Europe it is sadly common, and there had never been any cure for it.  Ointments, burning, surgery—­they were all equally useless.  Once the wolf had buried its fangs in its victim, he was doomed to inevitable death.  The disease is, in fact, tuberculosis of the skin, and is the most dreadful of all the forms in which the white plague scourges mankind—­was, until one day Finsen announced to the world his second discovery, that lupus was cured by the simple application of light.

It was not a conjecture, a theory, like the red-light treatment for smallpox; it was a fact.  For two years he had been sending people away whole and happy who came to him in despair.  The wolf was slain, and by this silent sufferer whose modest establishment was all contained within a couple of small shanties in a corner of the city hospital grounds, at Copenhagen.

There was a pause of amazed incredulity.  The scientific men did not believe it.  Three years later, when the physician in charge of Finsen’s clinic told at the medical congress in Paris of the results obtained at the Light Institute, his story was still received with a polite smile.  The smile became astonishment when, at a sign from him, the door opened and twelve healed lupus patients came in, each carrying a photograph of himself as he was before he underwent the treatment.  Still the doctors could not grasp it.  The thing was too simple as matched against all their futile skill.

But the people did not doubt.  There was a rush from all over Europe to Copenhagen.  Its streets became filled with men and women whose faces were shrouded in heavy bandages, and it was easy to tell the new-comers from those who had seen “the professor.”  They came in gloom and misery; they went away carrying in their faces the sunshine that gave them back their life.  Finsen never tired, when showing friends over his Institute, of pointing out the joyous happiness of his patients.  It was his reward.  For not “science for science’s sake,” or pride in his achievement, was his aim and thought, but just the wish to do good where he could.  Then, in three more years, they awarded him the great Nobel prize for signal service to humanity, and criticism was silenced.  All the world applauded.

“They gave it to me this year,” said Finsen, with his sad little smile, “because they knew that next year it would have been too late.”  And he prophesied truly.  He died nine months later.

All that is here set down seems simple enough.  But it was achieved with infinite toil and patience, by the most painstaking experiments, many times repeated to make sure.  In his method of working Finsen was eminently conservative and thorough.  Nothing “happened” with him.  There was ever behind his doings a definite purpose for which he sought a way, and the higher the obstacles piled up the more resolutely he set his teeth and kept right on.  “The thing is not in itself so difficult,” he said, when making ready for his war upon the wolf, “but the road is long and the experiments many before we find the right way.”