 The historian, investigating an event in the past, makes a distinction between what may be called the outside and the inside of an event. By the outside of the event I mean everything belonging to it which can be described in terms of bodies and their movements: the passage of Caesar, accompanied by certain men, across a river called the Rubicon at one date, or the spilling of his blood across the floor of the senate-house at another. By the inside of the event I mean that in it which can only be described in terms of thought: Caesar’s defiance of Republican law, or the clash of constitutional policy between himself and his assassins. The historian is never concerned with either of these to the exclusion of the other. He is investigating not mere events (where by a mere event I mean one which has only an outside and no inside) but actions, and an action is the unity of the outside and the inside of an event. He is interested in the crossing of the Rubicon only in its relation to Republican law, and in the spilling of Caesar’s blood only in relation to a constitutional conflict. (IH 1993: 213)