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its persistence through successive generations； and it will acquire all
the characters of a new species。
But； on the other hand； if the conditions of life change in any degree；
however slight； B may no longer be that form which is best adapted to
withstand their destructive； and profit by their sustaining； influence；
in which case if it should give rise to a more competent variety （C）；
this will take its place and become a new species； and thus； by
'natural selection'； the species B and C will be successively derived
from A。
That this most ingenious hypothesis enables us to give a reason for many
apparent anomalies in the distribution of living beings in time and
space； and that it is not contradicted by the main phenomena of life
and organization appear to us to be unquestionable； and so far it must
be admitted to have an immense advantage over any of its predecessors。
But it is quite another matter to affirm absolutely either the truth or
falsehood of Mr。 Darwin's views at the present stage of the inquiry。
Goethe has an excellent aphorism defining that state of mind which he
calls 'Thatige Skepsis'aactive doubt。 It is doubt which so loves
truth that it neither dares rest in doubting； nor extinguish itself by
unjustified belief； and we commend this state of mind to students of
species； with respect to Mr。 Darwin's or any other hypothesis； as to
their origin。 The combined investigations of another 20 years may；
perhaps； enable naturalists to say whether the modifying causes and the
selective power； which Mr。 Darwin has satisfactorily shown to exist in
nature； are competent to produce all the effects he ascribes to them；
or whether； on the other hand； he has been led to over…estimate the
value of his principle of natural selection； as greatly as Lamarck
overestimated his vera causa of modification by exercise。
But there is； at all events； one advantage possessed by the more recent
writer over his predecessor。 Mr。 Darwin abhors mere speculation as
nature abhors a vacuum。 He is as greedy of cases and precedents as any
constitutional lawyer； and all the principles he lays down are capable
of being brought to the test of observation and experiment。 The path
he bids us follow professes to be； not a mere airy track； fabricated of
ideal cobwebs； but a solid and broad bridge of facts。 If it be so； it
will carry us safely over many a chasm in our knowledge； and lead us to
a region free from the snares of those fascinating but barren Virgins；
the Final Causes； against whom a high authority has so justly warned us。
〃My sons； dig in the vineyard；〃 were the last words of the old man in
the fable； and； though the sons found no treasure； they made their
fortunes by the grapes。
End