"The agreement of so many kinds of animals in a certain common structure,
which seems to be fundamental not only in their skeletons, but also
in the arrangement of the other parts - so that a wonderfully simple
typical form, by the shortening and lengthening of some parts, and
by the suppression and development of others, might be able to produce
an immense variety of species - allows a ray of hope, however faint,
to enter our minds, that here perhaps some result may be obtained,
by the application of the principle of the mechanism of nature (without
which there can be no natural science in general). This analogy of
forms, which with all their differences seem to have been produced
in accordance with a common prototype, strengthens our suspicions
of an actual blood-relationship between them in their derivation from
a common parent through the gradual approximation of one class of
animals to another - beginning with the one in which the principle
of purposiveness seems to be best authenticated, ie. man, and extending
down to the polyps, and from these even down to mosses and lichens,
and arriving finally at raw matter, the lowest stage of nature observable
by us."
-- Immanuel Kant, Critique of Judgement, 1790
