§ 53. Only when we rightly comprehend the process of life may we know
how to live aright. Life, the "circle of eternal change," is constantly
transforming the inorganic into the organic, and after using it,
returning it again to the realm of the inorganic. Whatever it does not
assimilate of that which it has taken in simply as a stimulant, and
whatever has become dead, it separates from itself and rejects. The
organism is in perfect health when it accomplishes this double task of
organizing and disorganizing. On the comprehension of this single fact
all laws of physical health or of hygiene are based. This idea of the
essence of life is expressed by Goethe in his Faust, where he sees the
golden buckets perpetually rising and sinking.[13] When the equilibrium
of the upward and downward motion is disturbed, we have disease. When
the motion ceases we have death, in which the whole organism becomes
inorganic, and the "dust returns to dust."
§ 54. It follows from this that not only in the organism as a whole, but
in every organ, and every part of every organ, this restless change of
the inorganic to the organic is going on. Every cell has its own
history, and this history is only the same as that of the whole of which
it forms a part. Activity is then not inimical to the organism, but is
the appointed means by which the progressive and retrogressive
metamorphoses must be carried out. In order that the process may go on
harmoniously, or, in other words, that the body may be healthy, the
whole organism, and every part of it in its own way, must have its
period of productive activity and then also its period of rest in which
it finds renewal of strength for another period of activity. Thus we
have waking and sleep, inspiration and expiration of air. Periodicity is
the law of life. When we understand the relative antagonism (their stage
of tension) of the different organs, and their cycles of activity, we
shall hold the secret of the constant self-renewal of life. This thought
finds expression in the old fairy stories of "The Search after the
Fountain of Youth." And the figure of the fountain, with its rising and
falling waters, doubtless finds its origin in the dim comprehension of
the endless double movement, or periodicity of life.
§ 55. When to any organ, or to the whole organism, not sufficient time
is allowed for it to withdraw into itself and to repair waste, we are
conscious of fatigue. While the other organs all rest, however, one
special organ may, as if separated from them, sustain a long-continued
effort of activity even to the point of fatigue, without injury--as,
_e.g._, the lungs in talking while all the other members are at rest.
But, on the other hand, it is not well to talk and run at the same time.
The idea that the body may be preserved in a healthy state longer by
sparing it--_i.e._, by inactivity--is an error which springs from a
false and mechanical conception of life. It is just as foolish to
imagine that health depends on the abundance and excellence of food, for
without the power of assimilating the food taken, nourishment of
whatever kind does more harm than good; all real strength develops from
activity alone.
§ 56. Physical education, according as it relates to the repairing, the
muscular, or the emotional activities, is divided into (1) diatetics,
(2) gymnastics, (3) sexual education. In the direct activity of life
these all interact with each other, but for our purposes we are obliged
to speak of them as if they worked independently. Moreover, in the
development of the human being, they come into maturity of development
in a certain order: nutrition, muscular growth, sexual maturity. But
Pedagogics can treat of these only as they are found in the infant, the
child, and the youth; for with the arrival of mature life, education is
over.