Theoretical certitude is assimilated to practical certainty j to securityytrustworthiness of instrumental operations. "Real" things may be as transitory as you please or as lasting in time as you please; these are specific differences like that between aflash of lightning and the history of amountain range. In any case they are for knowledge "events" not substances. What knowledge is interested in is the correlation* among these changes or events which means in effect that the event called the mountain range must be placed within asystem consisting of avast multitude of included events. When these correlations are discovered, the possibility of control is in our hands. Scientific objects as statements of these inter-relations are instrumentalities of control. They are objects of the thought of reality, not disclosures of immanent properties of real sub- stances. They are in particular the thought of reality from a particular point of view: the most highly generalized view of nature as asystem of interconnected changes.