fine adjustments of larger ones is as near mental training as physical
culture can get; for these are the thought-muscles and movements, and
their perfected function is to reflect and express by slight
modifications of tension and tone every psychic change. Only the brain
itself is more closely and immediately an organ of thought than are
these muscles and their activity, reflex, spontaneous, or imitative in
origin. Whether any of them are of value, as Lindley thinks, in
arousing the brain to activity, or as Mueller suggests, in drawing off
sensations or venting efferent impulses that would otherwise distract,
we need not here discuss. If so, this is, of course, a secondary and
late function--nature's way of making the best of things and utilizing
remnants.

With these facts and their implications in mind we can next pass to
consider the conditions under which the adolescent muscles best
develop. Here we confront one of the greatest and most difficult
problems of our age. Changes in modern motor life have been so vast
and sudden as to present some of the most comprehensive and
all-conditioning dangers that threaten civilized races. Not only have
the forms of labor been radically changed within a generation or two,
but the basal activities that shaped the body of primitive man have
been suddenly swept away by the new methods of modern industry. Even
popular sports, games, and recreations, so abundant in the early life
of all progressive peoples, have been reduced and transformed; and the
play age, that once extended on to middle life and often old age, has
been restricted. Sedentary life in schools and offices, as we have
seen, is reducing the vigor and size of our lower limbs. Our industry
is no longer under hygienic conditions; and instead of being out of
doors, in the country, or of highly diversified kinds, it is now
specialized, monotonous, carried on in closed spaces, bad air, and