.

The world is a living fire, as Heraclitus long ago put it. All things
are in perpetual flux. Life is a process of perpetual movement. It is
idle to bid the world stand still, and then to argue about the
consequences. The world will not stand still, it is for ever revolving,
for ever revealing some new facet that had not been allowed for in the
neatly arranged mechanism of the statistician.

It is perhaps unnecessary to dwell on a point which is now at last, one
may hope, becoming clear to most intelligent persons. But I may perhaps
be allowed to refer in passing to an argument that has been brought
forward with the wearisome iteration which always marks the progress of
those who are feeble in argument. The good stocks of upper social class
are decreasing in fertility, it is said; the bad stocks of lower social
class are not decreasing; therefore the bad stocks are tending to
replace the good stocks.[11]

It must, however, be pointed out that, even assuming that the facts are
as stated; it is a hazardous assumption that the best stocks are
necessarily the stocks of high social class. In the main no doubt this
is so, but good stocks are nevertheless so widely spread through all
classes--such good stocks in the lower social classes being probably the
most resistent to adverse conditions--that we are not entitled to regard
even a slightly greater net increase of the lower social classes as an
unmitigated evil. It may be that, as Mercier has expressed it, "we have
to regard a civilized community somewhat in the light of a lamp, which
burns at the top and is replenished from the bottom."[12]

The soundness of a stock, and its aptitude for performing efficiently
the functions of its own social sphere, cannot, indeed, be accurately
measured by any tendency to rise into a higher social sphere. On the
whole, from generation to generation, the men of a good stock remain
within their own social sphere, whether high or low, adequately
performing their functions in that sphere, from generation to
generation. They remain, we may say, in that social stratum of which the
specific gravity is best suited for their existence.[13]

Yet, undoubtedly, from time to time, there is a slight upward social
tendency, due in most cases to the exceptional energy and ability of
some individual who succeeds in permanently lifting his family into a
slightly higher social stratum.[14] Such a process has always taken
place, in the past even more c