Comenius has some sound advice for mothers on the kinds of food for young children. At the first it must as nearly as possible approximate to their natural aliment; it must be soft, sweet, and easily digestible. Milk is an excellent food; and after milk, bread, butter, and vegetables. All highly seasoned foods are to be avoided; and Comenius urges mothers to regard medicines as they would poisons, and avoid them altogether. Children accustomed to medicine from their earliest years are certain to become “feeble, sickly, infirm, pale-faced, imbecile, cancerous.” Children during the earliest years require an abundance of sleep, fresh air, and exercise. They need not only to be exercised, but their exercises should be in the nature of amusements. “A joyful mind,” he remarks, “is half health, and the joy of the heart is the very life-spring of the child.” These exercises for the amusement of the child may provide for the pleasure of its eyes, ears, and other senses, as well as contribute to the vigor of its body and mind. Play not only conduces to the health of the child, but it lays the basis for later development.[34] _Mental Training_ For the mental training of the child during its first six years Comenius has outlined two classes of studies: (1) those which furnish the materials of thought, such as nature study, geography, and household economy, and (2) those which furnish the symbols of thought, such as drawing, writing, and language. This grouping of form and content studies, it should be noted, has been followed by the disciples of Herbart in their schemes of classification. The first and second years of the child’s life must be entirely given over to the development of organic functions; but, by the beginning of the third year, the child has acquired a vocabulary, and he should be taught to comprehend the meaning of the words he uses. This early knowledge should be of natural things—plants, flowers, trees, sand, clay, the cow, horse, and dog. He may be taught to comprehend some of the more important observable characters of these objects and to know their uses. Special exercises should be provided for the training of the eye; excessive lights must be avoided, and also overstraining. Children may be moderately introduced to objects of color, and thus taught to enjoy the beauty of the heavens, trees, flowers, and running water. In the fourth and following years they should be taken into fields and along the rivers, and trained to observe plants, animals, running water, and the turning of windmills. In both nature study and geography Comenius anticipated the _Heimatskunde_ of Pestalozzi. Children should also during their first six years be taught to know the heavens, and to distinguish between sun, moon, and stars; to understand that the sun and moon rise and set; to recognize that the days are shortest in winter and longest in summer; to distinguish time—morning, noonday, evening, and when to eat, sleep, and pray.