A new derivation of classical response theory is presented from the Heisenberg point of view, where observable properties are followed along a classical manyhyphen;body trajectory. The exact equivalence of the Heisenberg (observable) and Schrouml;dinger (distribution function) pictures is shown and the nature of their relationship is clarified. The formal expression is derived for the response to timehyphen;dependent external fields, to all orders.
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