ided these
are marks of many other properties, though certainly then there should
be also some more obvious property to act as a mark of the unobvious
ones which form the real basis.

As the first principle of _natural_ classification is that the classes
must be so formed that the objects composing each may have as many
properties in common as possible to serve as predicates, all _kinds_
should have places among the _natural_ groups, since the common
properties of _kinds_, and, therefore, the general assertions that can
be made about them, are innumerable. But _kinds_ are too few to make up
the whole of a classification: other classes also may be eminently
_natural_, though marked out from each other only by a definite number
of properties. Of neither sort of _natural_ groups is Dr. Whewell's
theory _strictly_ true, viz. that every _natural_ group is not
determined by definition, that is, by definite characters which can be
expressed in words, but is fixed by Type. He explains that a type is an
example of any class, for instance, a species of a genus, which
possesses all the characters and properties of the genus in a marked
way; that round this type-species are grouped all the other species,
which, though deviating from it in various directions and degrees, yet
are of closer affinity to it than to the centre of any other group; and
that this is the reason why propositions about _natural_ groups so often
state matters as being true not in all cases, but only in most. Now,
there is a truth, but only a partial truth, in this doctrine. It is
this: in forming _natural_ groups, species which want certain of the
class-characters, some one, and others another, are classed with those
(the majority) that have them all, because they are more like (that is,
in fact, have more of the common characters of) that particular group
than of any other. On account of the feeling of vagueness hence
engendered, we certainly, in deciding if an object belong to the group,
do generally (and _must_, when the classification is made expressly with
a view to a special inductive enquiry) refer mentally, not as a
substitute for, but in illustration of the definition of the group, to
some standard specimen which has _all_ the characters well developed.
But not the less, therefore, are all _natural_, equally with all
artificial, groups framed with distinct reference to certain definite
characters. In the case of _kinds_, a few characters are chosen as