“But, Strong, few of us go blind,” said Mr. Clyde. “And of those who do, nearly half are needlessly so. That we aren’t all groping, sightless, about the earth is due to the marvelous adaptability of our eyes. And it is exactly upon that adaptability that we are so prone to impose; working a willing horse to death. In the young the muscles of accommodation, whereby the vision is focused, are almost incredibly powerful; far more so than in the adult. The Cherub, here, could force her vision to almost any kind of work and the eye would not complain much—at this time. But later on the effects would be manifest. Therefore we have to watch the eye very closely until it begins to grow old, which is at about twelve years or so. In the adult the eye very readily lets its owner know if anything is wrong. Only fools disregard that warning. But in the developing years we must see to it that those muscles, set to the task of overcoming generations of custom, do not overwork and upset the whole nervous organization. Sometimes glasses are necessary; usually, only care.” “In a few generations we’ll all have four eyes, won’t we?” asked Bobs, making a pair of mock spectacles with his circled fingers and thumbs. “Oh, let’s hope not. The cartoonists of prophecy always give the future man spectacles. But I believe that the tendency will be the other way, and that, by evolution to meet new conditions, the eye will fit itself for its work, unaided, in time. Meantime, we have to pay the penalty of the change. That’s a small price for living in this wonderful century.” “You say that half the blind are needlessly so,” said Mrs. Clyde. “Is that from preventable disease?” “About forty per cent, of the wholly blind. But the half-blind and the nervously wrecked victims of eye-strain owe their woes generally to sheer carelessness and neglect. By the way, eye-strain itself may cause very serious forms of disease, such as obstinate and dangerous forms of indigestion, insomnia, or even St. Vitus’s dance and epilepsy.” “But you’re not telling us anything about eye diseases, Dr. Strong,” said Julia. “There speaks our Committee on School Conditions, filled full of information,” said the Health Master with a smile. “Junkum has made an important discovery, and made it in time. She has found that two children recently transferred from Number 14 have red eyes.” “Maybe they’ve been crying,” suggested Bettykin. “They were when I saw them, acute Miss Twinkles, although they didn’t mean it at all. One was crying out of one eye, and one out of the other, which gave them a very curious, absurd, and interesting appearance. They had each a developing case of pink-eye.” “Horses have pink-eye, not people,” remarked Grandma Sharpless.