be used relatively; and these may, for distinction, be called
Correlatives. But other words, whose meanings are only partially
interdependent, may often be used without attending to their relativity,
and may then be considered as Absolute. We cannot say 'the hunter
returned empty handed,' without implying that 'the prey escaped'; but we
may say 'the man went supperless to bed,' without implying that 'the
chamois rejoiced upon the mountain.' Such words as 'man' and 'chamois'
may, then, in their use, be, as to one another, non-relative.

To illustrate further the relativity of terms, we may mention some of
the chief classes of them.

Numerical order: 1st, 2nd, 3rd, etc.; 1st implies 2nd, and 2nd 1st;
and 3rd implies 1st and 2nd, but these do not imply 3rd; and so on.

Order in Time or Place: before-after; early-punctual-late;
right-middle-left; North-South, etc.

As to Extent, Volume, and Degree: greater-equal-less;
large-medium-small; whole and part.

Genus and Species are a peculiar case of whole and part (_cf._ chaps.
xxi.-ii.-iii.). Sometimes a term connotes all the attributes that
another does, and more besides, which, as distinguishing it, are called
differential. Thus 'man' connotes all that 'animal' does, and also (as
_differentiae_) the erect gait, articulate speech, and other attributes.
In such a case as this, where there are well-marked classes, the term
whose connotation is included in the others' is called a Genus of that
Species. We have a Genus, triangle; and a Species, isosceles, marked off
from all other triangles by the differential quality of having two equal
sides: again--Genus, book; Species, quarto; Difference, having each
sheet folded into four leaves.

There are other cases where these expressions 'genus' and 'species'
cannot be so applied without a departure from usage, as, e.g., if we
call snow a species of the genus 'white,' for 'white' is not a
recognised class. The connotation of white (i.e., whiteness) is,
however, part of the connotation of snow, just as the qualities of
'animal' are amongst those of 'man'; and for logical purposes it is
desirable to use 'genus and species' to express that relativity of
terms which consists in the connotation of one being part of the
connotation of the other.

Two or more terms whose connotations severally include that of another
term, whilst at the same time exceeding it, are (in relation to that
other term) called Co-ordinate. Thus in relation to