CONTINUITY IN EVOLUTION 337 
thought was evolved. For such thought it is essential that 
attention should be focussed on the relationships of things. 
And no description is possible without making distinctly 
present to consciousness these relationships, in time and space, 
the data for which are abundantly present in the perceptual 
life, though lurking in the background, and needing something 
to fix them and to aid consciousness in distinguishing them 
clearly. In descriptive communication parts of speech, or 
their initial equivalents, afford fixation points for these relation- 
ships, and serve to render them distinct. If the reader will 
try to describe even the simplest occurrence without introducing 
the symbols for the relations which the events bea: to each 
other, his failure will serve to bring home how essential a 
feature this is. In social communication, then, we probably 
have the key to the passage from perceptual to ideational 
process ; and in this passage description is the antecedent of, 
and affords the conditions to, explanation. Words, moreover, 
as we have already said, form the pegs upon which we can 
hang up, for ready reference, the products of abstraction and 
generalization, or, to modify the analogy, they form the bodies 
of which these products are the rational soul. 
If we are ever to trace the passage from the instinctive 
through the indicating stage of communication, and so onwards 
through the beginnings of description to its higher levels, and 
thus to the use of language as a medium of explanation, it 
must be through child-study. In every normal human child 
the passage does actually take place, though, no doubt, in a 
condensed and abbreviated form as an epitomized recapitula- 
tion in individual development, of the steps of evolutional 
progress. Thus we may obtain a key to the solution of one 
of the most difficult problems in evolution by continuous 
process—that of the transition from animal behaviour to 
human conduct. 
