th had been unusually free from such epidemics and had a
correspondingly low mortality, showing clearly that even the survivors
of children's diseases were not only not benefited, but distinctly
handicapped and set back in their growth by the energy, so to speak,
wasted in resisting the onslaught.

This brings us to an aspect of these diseases which from both a
philosophic and a practical point of view is most interesting and
profoundly significant; and that is the question with which we opened:
Why is a disease a disease of childhood? The old, primitive view was as
guileless and as simple as the age in which the diseases occurred. They
were regarded not merely by the laity but by grave and reverend
physicians of the Dark Ages as a sort of necessary vital crisis peculiar
and appropriate to each particular age of life,--a sort of sweating out
and erupting of "peccant humors" of the blood, which must be got rid
of or else the individual would not thrive. Incredible as it may
seem, so far was this idea extended, that the great Arabian
physician-philosopher, Rhazes, actually included smallpox in this group,
as the last of the "crises of growth" which had to appear and have its
way in young manhood or womanhood. Quaint little echoes of this simple
faith still ring in the popular mind, as, for instance, in the
widespread notion about the dangerousness of doing anything to check the
eruption in measles and cause it to "strike in." Any mother in Israel
will tell you, the first time you propose a bath or a wet pack to reduce
the temperature in measles, that if you so much as touch water to the
skin of that child it will "drive the rash in" and cause it to die in
convulsions. And, of course, one of the commonest of a physician's
memories is the expression of relief from the mother or aunt in any of
these mild eruptive fevers, where the skin was well reddened and
spotted: "Well, anyway, doctor, it is a splendid thing to get the rash
so well out!" Until within the last ten or fifteen years it was no
uncommon thing to hear the expression: "Well, I suppose we might just as
well let Willie and Susie go on to school and get the measles and have
done with it. It seems to be a real mild sort this time." Of course this
view was scientifically shattered two or more decades ago by our
recognition of the infectious nature of these diseases, but practically
its hold on the public mind constitutes one of the most serious and
vital obstacles in