how do we know that the sky is blue and the grass is green?must we wait for someone to teach us?no, we can observe the colors of the flowers and the hills and the sky with our eyes. through these windows, we can recognize the world about us. we can read books and papers, watch television, and see far into the distance--all with our eyes.
the eyes are delicate organs;therefore,we should be careful with them. in the first place, we should be careful to see that conditions are right when using our eyes in close work. many of us read a great deal, and when reading or studying , we should be very careful to have enough light. a bright, direct light is best, and it shoule shine upon the page without making a reflection.
we should also protect our eyes from heat, dust wind, and glare. we can help to keep our eyes free from dirt by using a clean towel or a handkerchief when we must wipe them. if the eyes are injured, we should go to an ete doctor as soon as possible.