The reason it is important to rest and to sleep enough is because it is while at rest that the body regains energy lost during activity, and stores it up for future work and play. There are other ways of saving energy, and one of them is by keeping the body in such good repair that like a good machine it does its work with a minimum expenditure of force and heat. This is the main reason for the setting-up exercises, or indeed for any sort of exercises. Perhaps the single best way to save energy is by saving your eyes. There is almost no work or play that does not involve the use of our eyes. If people are blind they can learn to do many things without vision, but it is infinitely harder than with it. Modern life, especially in cities, makes a constant demand on our eyes, and more than this, the demand is on one part of the eyes--the muscles concerned in near work. The best way to rest the eyes, and one which not only rests the tired parts but exercises the parts that are not used, is by doing things that will involve _distant vision_. Walking and looking far ahead and far away on every side rests the eyes best of all, and this is one reason why a good walk will often clear up a headache. Another way to insure distant vision is by riding backward in a car. Then as the landscape flows past you, your eye muscles relax to the position needed for distant vision. If you cannot walk or ride and are doing close work, like sewing or reading, look up and "at nothing" every once in a while. The following are some important rules to remember in saving your eyes: Rest your "near" eye muscles by looking at distant objects and places. Do not work facing a light or where the rays from a light cross your field of vision directly. Work so far as possible by indirect or reflected light. If you must work near uncovered artificial lights, wear an eye-shade. When sewing or writing have the light at your left, unless you are left-handed. This is to keep the shadow of your hands from the work. Avoid a glare or light that is in streaks or bars of alternate dark and bright. Diffused, even light is best. Have your eyes examined by a competent oculist immediately: If you have headaches, If the eyes sting or burn after using, If print or other objects dance or blur, If you must get close to your work to see it, If near work tires your eyes or you, If there is the slightest irritation or soreness about the lids or other parts. How to Avoid Muscle Strain