t the man of science can do, is
to reduce the difference between the foreseen and the actual results to
an unimportant quantity.

Moreover, it must be borne in mind not only that all the sciences are
qualitative in their first stages,--not only that some of them, as
Chemistry, have but recently reached the quantitative stage--but that
the most advanced sciences have attained to their present power of
determining quantities not present to the senses, or not directly
measurable, by a slow process of improvement extending through thousands
of years. So that science and the knowledge of the uncultured are alike
in the nature of their previsions, widely as they differ in range; they
possess a common imperfection, though this is immensely greater in the
last than in the first; and the transition from the one to the other has
been through a series of steps by which the imperfection has been
rendered continually less, and the range continually wider.

These facts, that science and the positive knowledge of the uncultured
cannot be separated in nature, and that the one is but a perfected and
extended form of the other, must necessarily underlie the whole theory
of science, its progress, and the relations of its parts to each other.
There must be serious incompleteness in any history of the sciences,
which, leaving out of view the first steps of their genesis, commences
with them only when they assume definite forms. There must be grave
defects, if not a general untruth, in a philosophy of the sciences
considered in their interdependence and development, which neglects the
inquiry how they came to be distinct sciences, and how they were
severally evolved out of the chaos of primitive ideas.

Not only a direct consideration of the matter, but all analogy, goes to
show that in the earlier and simpler stages must be sought the key to
all subsequent intricacies. The time was when the anatomy and physiology
of the human being were studied by themselves--when the adult man was
analysed and the relations of parts and of functions investigated,
without reference either to the relations exhibited in the embryo or to
the homologous relations existing in other creatures. Now, however, it
has become manifest that no true conceptions, no true generalisations,
are possible under such conditions. Anatomists and physiologists now
find that the real natures of organs and tissues can be ascertained only
by tracing their early evolution; and that