According to modern concepts the earth is divided into sovereign states. The sovereign states form a state system. They communicate by diplomacy and express their mutual recognition by establishing diplomatic relations. In practice, by mutually accrediting a permanent representative at the seat of government.

All these concepts were very new or fully unknown around 1600. But there existed a diplomatic practice consisting of a number of tools. The most basic of these was the letter. The development of relations between the Netherlands and Denmark 1568-1632 shows how the increasing use and sophistication of these tools developed into a cultural pattern which, expressed in the words used today, constituted mutual diplomatic recognition.