See Collected Essays, vol. ii. pp. 461-89; vol. iii.
p. 33; vol. viii. p. 304. In the address on "Geological
Contemporaneity and Persistent Types" (1862), the
paleontological proofs of this proposition were, I believe,
first set forth.
That the state of nature, at any time, is a temporary phase of a
process of incessant change, which has been going on for innumerable
ages, appears to me to be a proposition as well established as any in
modern history.
Paleontology assures us, in addition, that the ancient philosophers
who, with less reason, held the same doctrine, erred in supposing that
the phases formed a cycle, exactly repeating the past, exactly
foreshadowing the future, in their rotations. On the contrary, it
furnishes us with conclusive reasons for thinking that, if every link
in the ancestry of these humble indigenous plants had been preserved
and were accessible to us, the whole would present a converging series
of forms of gradually diminishing complexity, until, at some period in
the history of the earth, far more remote than any of which organic
remains have yet been discovered, they would merge in those low groups
among which the Boundaries between animal and vegetable life become
effaced.*
* "On the Border Territory between the Animal and the Vegetable
Kingdoms," Essays, vol.
Pages:
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33