    Sentence I: Vygotsky's theory has been the:wellspring of.  oitt-recént appreciation of the profoundly’ social nature of  even very young chifdrén'siinaginative pay'and its wide:  rdnging infiuence‘on cognitive arid: social development.    Sentence 2 Our recognition of the social aspects.of make-  believe in. young children is actually recent.         Be