756. The natural world contains various things which can illustrate the ending of the age. For here every single thing upon the earth grows old and reaches its end, but in successive alternations known as cycles. Periods of time are cyclical, both in general and in detail. In general, the year advances from spring to summer, through this to autumn and comes to an end in winter, from which it returns to spring; this is the heat cycle. In detail, the day advances from morning to noon, through this to evening and comes to an end in night, from which it returns again to morning; this is the light cycle. Every human being too goes through a natural cycle. He begins his life from childhood, advances to adolescence and early adulthood, from which he passes into old age, and dies. Likewise every bird of the sky, and every beast of the earth. Every tree too begins with a shoot, grows to full size and little by little wastes away, until it falls. The same thing happens to every shrub and plant, in fact to every leaf and flower, as well as to the ground itself, which in course of time becomes barren. The same happens to every stretch of still water, which little by little becomes foul. All of these endings are alternating, being natural and temporary, but they show periodicity. For when one passes from its beginning to its end, another like it arises. So everything is born and wastes away, and is born again, so that creation may continue in existence. The reason why much the same happens to the church is that people are a church, and on the general level compose it. One generation takes the place of another, and every mind is different. Wickedness once rooted in the character is transferred to descendants as a propensity to wickedness; and it cannot be rooted out except by regeneration, which only the Lord can bring about.