Progress
The observer of Nature makes a third discovery. Every fresh cycle of
life is characterised by an advance on the preceding cycle; every
stage brings the end nearer. This represents progress, and it is seen
everywhere; when it does not appear, it is because our limited vision
cannot pierce its veil. Minerals slowly develop in the bowels of the
earth, and miners well know when the ore is more or less "ripe,"[45]
and that
ertain portions, now in a transition stage, will in a
certain number of centuries have become pure gold; experiments[46]
have proved that metals are liable to "fatigue" from excessive
tension; and that, after a rest, they acquire greater power of
resistance than before; magnets "are fed," i.e., they increase their
power of attraction, by exercise; cultivation improves and sometimes
altogether transforms certain species of vegetables; the rapid mental
development of domestic animals by contact with man is a striking
instance of the heights to which progress may attain when it is aided,
whilst the influence of teaching and education on the development of
individuals as well as of races is even more striking.[47]