the affinities between
existing genera can be satisfactorily made out only by examining the
fossil genera to which they are allied. Well, is it not clear that the
like must be true concerning all things that undergo development? Is not
science a growth? Has not science, too, its embryology? And must not the
neglect of its embryology lead to a misunderstanding of the principles
of its evolution and of its existing organisation?

There are _a priori_ reasons, therefore, for doubting the truth of all
philosophies of the sciences which tacitly proceed upon the common
notion that scientific knowledge and ordinary knowledge are separate;
instead of commencing, as they should, by affiliating the one upon the
other, and showing how it gradually came to be distinguishable from the
other. We may expect to find their generalisations essentially
artificial; and we shall not be deceived. Some illustrations of this may
here be fitly introduced, by way of preliminary to a brief sketch of the
genesis of science from the point of view indicated. And we cannot more
readily find such illustrations than by glancing at a few of the various
_classifications_ of the sciences that have from time to time been
proposed. To consider all of them would take too much space: we must
content ourselves with some of the latest.

* * * * *

Commencing with those which may be soonest disposed of, let us notice
first the arrangement propounded by Oken. An abstract of it runs
thus:--

Part I. MATHESIS.--_Pneumatogeny_: Primary Art, Primary
Consciousness, God, Primary Rest, Time, Polarity, Motion,
Man, Space, Point. Line, Surface, Globe,
Rotation.--_Hylogeny_: Gravity, Matter, Ether, Heavenly
Bodies, Light, Heat, Fire.

(He explains that MATHESIS is the doctrine of the whole;
_Pneumatogeny_ being the doctrine of immaterial totalities, and
_Hylogeny_ that of material totalities.)

Part II. ONTOLOGY.--_Cosmogeny_: Rest, Centre, Motion, Line,
Planets, Form, Planetary System, Comets.--_Stoechiogeny_:
Condensation, Simple Matter, Elements, Air, Water,
Earth--_Stoechiology_: Functions of the Elements, etc.,
etc.--_Kingdoms of Nature_: Individuals.

(He says in explanation that "ONTOLOGY teaches us the phenomena
of matter. The first of these are the heaven