THE PRINCIPLES OF BIOLOGY. 
208 
accurate grouping. In the history of the knowledge-relations 
of a race, the same principles are involved, and classificatory 
notions would go through a cycle of phases, at first exceed¬ 
ingly simple, gradually increasing in complexity and accuracy 
of differentiation ; individual qualities or attributes would be 
replaced by groups of qualities or attributes; objects posses¬ 
sing some of one and some of another group would have 
their attributes analysed, and comparative values would thus 
be given to each individual quality. The ultimate classifica¬ 
tion would therefore imply not merely knowledge of many 
attributes of the object in question, but the relative import¬ 
ance of these in some, at first no doubt empyrical, scale, and 
the mere position given to an object would give us the largest 
possible amount of information about it and its attributes. 
An illustration of the growth of the classificatory idea is 
afforded by the common dictionary or encyclopaedia. Itself 
the proof of great advance, in it, nevertheless, but one pro¬ 
perty, and that artificial in the extreme, viz., the order of the 
letters, is the key to the whole system, and “ Babj,” with its 
appendages, is found next door to “Babylon,” “Dog” to 
“Dogma,” “Hosier” to “Hospice” and “Hospital.” A 
step in advance is shown by a recently published Anglo- 
French Dictionary, where all the words of common root 
origin are kept together, and apart from all the words of 
other root origin. The highest stage of verbal classification 
is shown, perhaps, by such a work as the “ Thesaurus of 
English Words and Phrases ” of Dr. Boget, in which the 
words are systematically arranged according to their actual 
value and relations, whether abstract, or in space, matter, &c., 
and quite independently of root oiigin. But the inapplica¬ 
bility of such classifications to finite beings, in a subject in 
such general- use as language, is shown by the provision of 
an alphabetical glossary as a key to the whole. iSuch highly 
developed forms of classification emanate from, and appeal 
only to, the specialist. 
Natural objects of course come upon a different footing to 
words ; but here, too, probably the most perfect classification 
for specialists will be that which, based as far as may be on, 
to borrow our above phrase, common root origin, is leavened 
with a full share of present physiological and morphological 
meaning. 
These phases of classification are well illustrated by the 
biological sciences. The use of simple and conspicuous 
characters led to the classification of plants into trees, shrubs, 
and herbs, an arrangement still popularly clung to. Caesal- 
pinus (1588) slightly amplified this into trees, undershrubs, 
