oo great a weight loses strength, and may
break if subjected anew to the same weight that "fatigued" it. Pieces
of iron break after being "fatigued" by a weight they easily carried
before. Professor Kennedy made very useful experiments regarding the
"fatigue" of metals at the time when metallic bridges were continually
breaking, thus causing great perplexity in the engineering world.]

[Footnote 47: There has been much discussion as to the causes of
Evolution.

In his _Progress and Poverty_, Henry George endeavours to show that
Evolution is in no way brought about by individual or collective
heredity. He says that the factors of Progress are: First, the mind,
which causes the advance of civilisation when not exercised solely in
the "struggle for life," or in frequent conflicts between nation and
nation; second, association or combination, which ensures all the
benefits to be derived from division of work; third, justice, which
harmonises the units of the social body, and without which
civilisation decays and dies.

H. George saw only these elements in evolution; consequently, he could
neither solve the problem of progress nor explain the rise and fall of
empires. Indeed, egoism and war are in no way, as he says they are,
the sole causes of the fall of races: the soil cannot feed a great
nation for an indefinite period even if the country is prevented by
emigration from becoming over-populated; the very nature itself of the
civilisation of the time prevents it from continuing for ever. Modern
western races, for instance, have for centuries past been developing
energy and intelligence; a limit must be fixed to that particular line
of progress, under penalty of destroying equilibrium both in the
individual and the race.

If, indeed, man is to learn strength and intelligence, he must also
develop love, or he will fail. The Elder Brothers behind Evolution
control the advance of the races in accordance with the plan of God,
whose servants they are.

The real cause of evolution does not lie in environment, as H. George
and his school would have it: it is in the divine Will, incarnate in
the Universe. It is God who creates the world, God who fills it with
life, guides it and permits its development. All the laws of Nature
are the expression of the supreme Intelligence; all progress is
nothing but the realisation of the possibilities of the divine Will.

The evolutionary edifice is based on solidarity, and here environmen