"The infant school should be found in every house, the vernacular school in every village and community, the gymnasium in every province, and the university in every kingdom or large province." This scheme, with variation of details, forms the basis of present school systems: first, the period in the home with the mother till six; second, the period of general education in the common school, from six to twelve or fourteen; third, the period of preparation for the professional schools, from twelve or fourteen to eighteen; and fourth, the professional or university course, from eighteen to twenty-four. The last is usually divided into a college and a university course. (3) The educational principles of Comenius were revolutionary as to the school practices of the time. They have come to be almost universally accepted at present. We can here state only a few of the most essential.[104] 1. If we would teach and learn surely, we must follow the order of Nature. 2. Let everything be presented through the senses. 3. Proceed from the easy to the difficult, from the near to the remote, from the general to the special, from the known to the unknown. 4. Make learning pleasant by the choice of suitable material, by not attempting too much, by the use of concrete examples, and by the selection of that which is of utility. 5. Fix firmly by frequent repetitions and drills. 6. Let all things advance by indissoluble steps, so that everything taught to-day may give firmness and stability to what was taught yesterday, and point the way to the work of to-morrow.[105] 7. Let everything that is useless be eliminated from teaching. 8. Learn to do by doing. 9. Each language should be learned separately, have a definite time assigned to it, be learned by use rather than precept,--that is, the practice in learning should be with familiar things,--and all tongues should be learned by one and the same method. 10. The example of well-ordered life of parents, nurses, teachers, and schoolfellows is very important for children; but precepts and rules of life must be added to example. 11. As knowledge of God is the highest of all knowledge, the Holy Scriptures must be the alpha and omega of the Christian schools. Comenius gives explicit directions as to methods of instruction, class management, discipline, courses of study, including a discussion of each branch, and moral and religious teaching. He presents these directions in the most remarkable and complete series of precepts and principles to be found in educational literature.[106] MILTON (1608-1674)