For past actions or states, the simple past is generally used: "He went out an hour ago"; "Columbus knew the shape of the world". However, for completed actions for which no past time frame is implied or expressed, the present perfect is normally used: "I have made the dinner" (i.e. the dinner is now ready). For an action in the course of taking place, or a temporary state existing, at the past time being referred to (compare uses of the present progressive above), the past progressive is used: "We were sitting on the beach when..." For an action that was completed before the past time being referred to, the past perfect is used: "We had sat down on the blanket when..."