yed,
by a constant experience of good fortune, into rashness and
heedlessness, because they trust to their luck and depend upon their
fortunate star.

But the man who is of an energetic and active type, if he is haunted by
anxiety, if his imagination paints the possibilities of disaster, takes
every means in his power to foresee contingencies, and to deal
cautiously and thoroughly with the situation which causes him anxiety.
If he is a man of keen sensibilities, the pressure of such care is so
insupportable that he takes prompt and effective measures to remove it;
and his fear thus becomes an element in his success, because it urges
him to action, and at the same time teaches him the need of due
precaution. As Horace wrote:

"Sperat infestis, metuit secundis
Alteram sortem."

"He hopes for a change of fortune when things are menacing, he fears a
reverse when things are prosperous." And if we look at the facts of
life, we see that it is not by any means the confident and optimistic
people who succeed best in their designs. It is rather the man of eager
and ambitious temperament, who dreads a repulse and anticipates it, and
takes all possible measures beforehand to avoid it.

We see the same principle underlying the scientific doctrine of
evolution. People often think loosely that the idea of evolution, in
the case, let us say, of a bird like a heron, with his immobility, his
long legs, his pointed beak, his muscular neck, is that such
characteristics have been evolved through long ages by birds that have
had to get their food in swamps and shallow lakes, and were thus
gradually equipped for food-getting through long ages of practice. But
of course no particular bird is thus modified by circumstances. A
pigeon transferred to a fen would not develop the characteristics of
the heron; it would simply die for lack of food. It is rather that
certain minute variations take place, for unknown reasons, in every
species; and the bird which happened to be hatched out in a fenland
with a rather sharper beak or rather longer legs than his fellows,
would have his power of obtaining food slightly increased, and would
thus be more likely to perpetuate in his offspring that particular
advantage of form. This principle working through endless centuries
would tend slowly to develop the stock that was better equipped for
life under such circumstances, and to eliminate those less suited to
the locality; and thus the fittes