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.” He took no new step before he had planted his foot firmly in the one that went before; but once he knew where he stood, he did not hesitate to question any scientific dogma that opposed him, always in his own quiet way, backed by irrefutable facts. In a remarkable degree he had the faculty of getting down through the husk to the core of things, but he rejected nothing untried. The little thing in hand, he ever insisted, if faithfully done might hold the key to the whole problem; only let it be done _now_ to get the matter settled. Whatever his mind touched it made perfectly clear, if it was not so already. As a teacher of anatomy he invented a dissecting knife that was an improvement on those in use, and clamps for securing the edges of a wound in an operation. As a rifle shot he made an improved breech; as a physician, observing the progress of his own disease, an effective blood powder for anaemia. At the Light Institute, which friends built for him, and the government endowed, he devised the powerful electric lamps to which he turned in the treatment of lupus, for the sun does not shine every day in Copenhagen; and when it did not, the lenses that gathered the blue rays and concentrated them upon the swollen faces were idle. And gradually he increased their power, checking the heat rays that would slip through and threatened to scorch the patient’s skin, by cunning devices of cooling streams trickling through the tubes and the hollow lenses. Nothing was patented; it was all given freely to the world. The decision which he and his wife made together was made once for all. When the great Nobel prize was given to him he turned it over to the Light Institute, and was with difficulty persuaded to keep half of it for himself only when friends raised an equal amount and presented it to the Institute.