why yet another biography of robert frost -lrb- 1874-1963 -rrb- , when more than a dozen lives of the poet have already been published , among them lawrance thompson 's three -volume official biography , `` robert frost : the early years , 1874-1915 , '' `` robert frost : the years of triumph , 1915-1938 '' and `` robert frost : the later years , 1938-1963 , '' the latter written with r.h. winnick ?