Buck Carl Darling. A Dictionary of Selected Synonyms in the Principal Indo-European Languages

Chicago: University of Chicago Press, 2008. — 471 p.The kind of thinking that distinguishes man from brute has been built up by and is dependent upon the use of symbols. Since vocal utterance attained a higher development than gesture as a means of communication, these symbols are, in fact, the words. Animals, to be sure, have cries which in some cases cover a very considerable range of emotions and to a certain extent serve to communicate. But these are limited to the immediate experience: they are not detachable symbols capable of expressing past or future experience or any abstract concept. Yet such cries, which comprise all that primitive man inherited from his ancestry, must perforce be the starting-point of human speech.