  If history is to be a science of human action and not to pretend to be a science of nature, then, Du Bois believes, it must take account of the subjective meanings of actions and events. Du Bois implies that the historian cannot truly tell the story of “the mightiest effort of the mightiest century” (the struggle of enslaved blacks to achieve democracy) without taking account of the “psychology” of the agents whose actions sustained that effort—for to take psychology into account is to take subjective meaning into account (1935, 586). More generally, Du Bois insists that the historian of slavery ask: “Just what did [slavery] mean to the owner and the owned”(1935, 585). 