tendencies of nature often run counter to one another, so that the
result to which this or that was tending is frustrated. But a tendency
is a tendency, although defeated; _this_ was for _that_, although that
for which it was has got perverted to something else. There is no
tendency which of itself fails and comes to naught, apart from
interference. Such a universal and absolute break-down is unknown to
nature.

6. All this appears most clearly in organic beings, plants and
animals. Organisms, except the very lowest, are compounds of a number
of different parts, each fulfilling a special function for the good of
the whole. There is no idle constituent in an organic body, none
without its function. What are called _rudimentary_ organs, even if
they serve no purpose in the individual, have their use in the
species, or in some higher genus. In the animal there is no idle
natural craving, or appetite. True, in the individual, whether plant
or animal, there are many potentialities frustrate and made void. That
is neither here nor there in philosophy. Philosophy deals not with
individuals but with species, not with Bucephalus or Alexander, but
with _horse_, _man_. It is nothing to philosophy that of a thousand
seeds there germinate perhaps not ten. Enough that one seed ever
germinates, and that all normal specimens are apt to do the like,
meeting with proper environment. That alone shows that seed is not an
idle product in this or that class of living beings.

7. But, it will be said, not everything contained in an organism
ministers to its good. There is refuse material, only good to get rid
of: there are morbid growths; there is that tendency to decay, by
which sooner or later the organism will perish. First, then, a word on
diseases. Diseases are the diseases of the individual; not of the