The problem that confronts us at the outset, when preparing a plan of concentration, is _how to select_ the best historical (moral educative) materials, which are to serve as the central series of the course. The _culture epochs_ (cultur-historische Stufen) are, according to the Herbartians, the key to the situation. (This subject was briefly discussed under _Interest_.)
According to the theory of the _culture epochs_, the child, in its growth from infancy to maturity, is an epitome of the world's history and growth in a profoundly significant sense for the purpose of education. From the earliest history of society and of arts, from the first simple family and tribal relations, and from the time of the primitive industries, there has been a series of upward steps toward our present state of culture (social, political, and economic life). Some of the periods of progress have been typical for different nations or for the whole race; for example, the stone age, the age of barbarism, the age of primitive industries, the age of nomads, the heroic age, the age of chivalry, the age of despotism, the age of conquest, wars of freedom, the age of revolution, the commercial age, the age of democracy, the age of discovery, etc. What relation the leading epochs of progress in the race bear to the steps of change and growth in children, has become a matter of great interest in education. The assumption of the _culture epochs_ is that the growth of moral and secular ideas in the race, represented at its best, is similar to their growth in children, and that children may find in the representative historical periods select materials for moral and intellectual nurture and a natural access to an understanding of our present condition of society. The culture epochs are those representative periods in history which are supposed to embody the elements of culture suited to train the young upon in their successive periods of growth. Goethe says, "Childhood must always begin again at the first and pass through the epochs of the world's culture." Herbart says, "The whole of the past survives in each of us," and again, "The receptivity (of the child) changes continually with progress in years. It is the function of the teacher to see to it that these modifications advance steadily in agreement with these changes (in the world's history)." Ziller has attempted more fully to "justify this culture-historical course of instruction on the ground of a certain _predisposition_ of the child's mental growth for this course." Again, "We are to let children pass through the culture development of mankind with accelerated speed." Herbart says, "The treasure of advice and warning, of precept and principle, of transmitted laws and institutions, which earlier generations have prepared and handed down to the latter, belongs to the strongest of psychological forces." That is, choice historical illustrations produce a weighty effect upon the minds of children, if selected from those epochs which correspond to a child's own periods of growth.