correlate as strictly
contemporaneous two formations, which do not include many identical
species, by the general succession of the forms of life.

As species are produced and exterminated by slowly acting and still
existing causes, and not by miraculous acts of creation; and as the most
important of all causes of organic change is one which is almost
independent of altered and perhaps suddenly altered physical conditions,
namely, the mutual relation of organism to organism--the improvement of
one organism entailing the improvement or the extermination of others;
it follows, that the amount of organic change in the fossils of
consecutive formations probably serves as a fair measure of the
relative, though not actual lapse of time. A number of species, however,
keeping in a body might remain for a long period unchanged, while within
the same period, several of these species, by migrating into new
countries and coming into competition with foreign associates, might
become modified; so that we must not overrate the accuracy of organic
change as a measure of time.

In the future I see open fields for far more important researches.
Psychology will be securely based on the foundation already well laid by
Mr. Herbert Spencer, that of the necessary acquirement of each mental
power and capacity by gradation. Much light will be thrown on the
origin of man and his history.

Authors of the highest eminence seem to be fully satisfied with the view
that each species has been independently created. To my mind it accords
better with what we know of the laws impressed on matter by the Creator,
that the production and extinction of the past and present inhabitants
of the world should have been due to secondary causes, like those
determining the birth and death of the individual. When I view all
beings as not special creations, but as the lineal descendants of some
few beings which lived long before the first bed of the Cambrian system
was deposited, they seem to me to become ennobled. Judging from the
past, we may safely infer that not one living species will transmit its
unaltered likeness to a distant futurity. And of the species now living
very few will transmit progeny of any kind to a far distant futurity;
for the manner in which all organic beings are grouped, shows that the
greater number of species in each genus, and all the species in many
genera, have left no descendants, but have become utterly extinct. We
can so far take