No field of thought can be properly laid out by men who are
merely measuring with a ruler. Sections of history are liable to be
transformed-or, even where not transformed, greatly vivifiedby an imagination that comes, sweeping like a searchlight, from
outside the- historical profession itself. Old hunches are then
confirmed by fresh applications of the evidence or by unexpected
correlations between sources. New matter emerges because things
are joined together which it had not occurred to one to see in
juxtaposition. New details are elicited, difficult details become
relevant, because of a fresh turn that the argument has taken.