With the surrender of unchangeable substances having properties fixed in isolation and unaffected by inter- actions, must go the notion that certainty is attained by attach- ment to fixed objects with fixed characters. For not only are no such objects found to exist, but the very nature of ex- perimental method, najmely, definition by operations that are interactions, implies that such things are not capable of being known. Henceforth the quest for certainty becomes the search for methods of control jthat is, reguktion of conditions of change with respect to their consequences.