There is a broad but not commonly recognized distinction between what constitutes a medicine and a food. All the materials that normally enter into the composition of the living body, and are necessary to the maintenance of health and strength, may be property classed as foods, whether they be obtained from the animal, vegetable, or mineral kingdoms; thus the iron, sulphur, phosphorus, lime, potash, etc., required by the system usually exist in and are organically combined with the various foods in common use, and they are perhaps quite as essential to the physical well-being as albuminoid, fatty, and saccharine matters. When the system is suffering from lack of any of the above mentioned chemicals, their administration is to be regarded as the giving of nutritive substances, although they be prescribed by a physician in divided doses and procured from a pharmacist. On the other hand, a medicine is any substance that does not naturally enter into the composition of the body, but which has the power, when skillfully used, to modify the physical processes so that physiological disorder--disease, shall be replaced by physiological harmony--health. Belladonna, hyoscyamus, opium, etc., are familiar examples of medicaments. Therefore a food is any substance that is capable of directly contributing to the nutrition of the body, and medicine is a substance competent, under proper conditions, to secure the same results indirectly. Viewed in the light of the above definition, cod-liver oil is to be regarded as a very valuable food, as well as a most effective remedy both for the prevention and cure of consumption.