 The important clue for answering this question is that these representations of objective simultaneity and succession are universal and necessary. It is the universality and necessity of our representing the parts of the house as simultaneous that accounts for our representing them as objectively simultaneous, and the universality and necessity of our representing the positions of the boat as successive that accounts for our representing them as objectively successive. Association is inadequate for accounting for this objectivity because it is incapable of yielding such universality and necessity, a defect not shared by synthesis.