s kind arrives in the spring
have stronger constitutions and greater powers of application than do
those conceived at any other season. Evidence of constitutional vigor is
found in length of life. In four large groups of Americans and in one of
Italians it has been found that those born in March, and therefore
conceived in June at the time of optimum weather, live longer than those
born at other seasons. Among 39,000 people who were born in the eastern
United States and who lived beyond the age of two years I found that on
an average those born in March lived 3.8 years longer than those born
from July to September.

Other evidence, into which we cannot go, suggests that man, like other
animals, inherits a definite seasonal cycle of reproduction. As the
temperature rises toward the optimum in the spring the functions of the
body change in such a way that not only is there a pronounced feeling of
well-being, but the children conceived at that time have more than the
average vigor, and hence correspondingly long life.

The evidence that these children have greater powers of application, or
at least that some of them do, lies in the birthdays of eminent people
in countries as diverse as India, Spain, Russia, England, France,
Germany, Sweden, and the United States. In all these countries the
percentage of eminent people conceived when the optimum weather prevails
rises much higher than does the corresponding percentage among ordinary
people. Moreover, the greater the degree of eminence, the more marked
is the contrast with people as a whole.

The reason for this condition must be that the vigor which gives to many
people long life gives to highly gifted people a sort of power of steady
application and hard work--an emotional stability--which enables them to
use their faculties to the best advantage. Thus they achieve fame in
greater measure than do equally well-endowed persons with less vigor.
There is not the slightest reason to suppose that children conceived at
one season of the year inherit any better minds than do their brothers
and sisters conceived at other seasons. There is equally little reason
to believe that the average inheritance of mental ability declines as
the period of conception approaches midwinter, the low point in the
seasonal cycle of reproduction. On the other hand, length of life
furnishes evidence that physical vigor varies according to the degree to
which the mothers at least, at the time of a chi