"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 fittest would tend to survive. But it does not indicate any design on the part of the birds themselves, nor any deliberate attempt to develop those characteristics; it is rather that such characteristics, once started by natural variation, tend to emphasize themselves in the lapse of time.