Lexical restrictions and pronoun distribution

“In the last analysis it is difficult to find a definition valid for all pronouns, though there is much in their often pecuiiar paradigms and usage to justify our setting them up as a separate word class" (Otto Jespersen). One of the peculiarities which serves to "justify" an interpretation of the pronoun (or, in this case, the Russian pronoun) as an independent word class is its completely unique distribution, that is, the syntactic combinations to which it lends itself