do this by showing that sensation logically arises out of nu-
trition. For a logical development is the same as a rational
development. He ought to have logically deduced sensation
from nutrition, and so with all the other forms. As it is,
all that can be said is that Aristotle was the founder of a
philosophy of evolution because he saw that evolution im-
plies movement towards an end, and because he attempted
to point out the different stages in the attainment of that
end, {338} but that he failed rationally to develop the doc-
trine stage by stage.
As neither the principle of form in general was shown to be
necessary, nor were the particular forms deduced from each
other, we have to conclude that Aristotle like Plato,named
a self-explanatory principle, reason or form, as ultimate
principle of things, but failed to show in detail that it is self-
explanatory. Yet, in spite these defects, the philosophy of
Aristotle is one of the greatest philosophies that the world
has ever seen, or is ever likely to see. If it does not solve
all problems, it does render the world more intelligible to
us than it was before.
{339}