VARIETIES OF HUMAN SPEECH SAPIR. 575 



practically immterrii})tcd series from the eighth century A. D. to the 

 present time, while the course of development of Greek in its various 

 dialects can be more or less accurately followed from the ninth cen- 

 tury B. C, a conservative date for the Homeric poems, to the present 

 time. 



For some, in fact for most languages, however, literary monuments 

 are either not forthcomhig at all or else are restricted to a single 

 period of short duration. At first sight it would seem that the sci- 

 entific study of such languages would have to be limited to purely 

 descriptive rather than historical data. To a considerable extent 

 this is necessarily true, yet an mtensive study will always yield at least 

 some, oftentimes a great deal of, information of a historical character. 

 This historical reconstruction on the basis of purely descriptive data 

 may proceed in two ways. It is obvious that the various phonetic 

 and grammatical features of a language at any given time are of 

 unequal antiquity, for they are the resultants of changes that have 

 taken place at very different periods; hence it is reasonable to 

 suppose that mternal evidence would, at least within modest limits, 

 enable one to reconstruct the relative chronology of the langua.ge. 

 Naturally one must proceed very cautiously in reconstructing by 

 means of internal evidence, but it is oftentimes surprising how much 

 the careful and methodically schooled student can accomplish in this 

 way. Generally speaking, linguistic features that are irregular in 

 character ma}^ be considered as relatively archaic, for they are in the 

 nature of survivals of features at one time more widely spread. Not 

 infrequently an inference based on internal evidence can be corrobo- 

 rated by direct historical testimony. One example will suffice here. 

 We have in English a mere sprinkling of noun plurals in -en, such as 

 hrethren and oxen. One may surmise that nouns such as these are but 

 the last survivals of a tyi^e formerly existing in greater abundance, 

 and indeed a study of Old English or Anglo-Saxon demonstrates that 

 noun plurals in -en were origmally found in great number but were later 

 almost entirely replaced by plurals in -s. There is, however, a far 

 more powerful method of reconstructing linguistic history from 

 descriptive data than internal evidence. This is the comparison of 

 genetically related languages. 



In making a survey of the spoken languages of the world, we soon 

 find that though they differ from each other, they do so in quite vary- 

 ing degrees. In some cases the differences are not great enough to 

 prevent the speakers of the two languages from understanding each 

 other with a fair degree of ease, under which circumstances we are apt 

 to speak of the two forms of speech as dialects of a single language; in 

 other cases the two languages are not mutually intelligible, but, as in 

 the case of English and German, present so many similarities of 

 detail that a belief in their common oiigin seems warranted and 



