XC.
An Artificial System is one in which the smaller groups (the Genera) are natural; and in which the wider divisions (Classes, Orders) are constructed by the peremptory application of selected Characters; (selected, however, so as not to break up the smaller groups.) (viii. 2.)
XCI.
A Natural System is one which attempts to make all the divisions natural, the widest as well as the narrowest; and therefore applies no characters peremptorily. (viii. 2.)
XCII.
Natural Groups are best described, not by any Definition which marks their boundaries, but by a Type which marks their center. The Type of any natural group is an example which possesses in a marked degree all the leading characters of the class. (viii. 2.) 22
XCIII.
A Natural Group is steadily fixed, though not precisely limited; it is given in position, though not circumscribed; it is determined, not by a boundary without, but by a central point within;—not by what it strictly excludes, but by what it eminently includes;—by a Type, not by a Definition. (viii. 2.)
XCIV.
The prevalence of Mathematics as an element of education has made us think Definition the philosophical mode of fixing the meaning of a word: if (Scientific) Natural History were introduced into education, men might become familiar with the fixation of the signification of words by Types; and this process agrees more nearly with the common processes by which words acquire their significations. (viii. 2.)