This article seeks to re-examine the intellectual context of commercial policy and regulation in seventeenth-century England. It questions a common assumption about so-called ‘mercantilist’ writers: that they saw trade as in some way finite and therefore won by one nation at the expense of another. Instead, it proposes that the often belligerent attitude of the ‘mercantilists’ towards trade was rooted in an understanding of the nature of international commerce as both communication and competition. Although writers acknowledged the mutual aspect of trade, they did not see this exchange as automatically equal, but saw it as possible for one party to exploit the other. This situation demanded state action to protect national trading interests in the disputed area of commerce, and thus this ‘discourse of trade’ was linked to political and juridical discourses about international relations. The article shows how this understanding of trade influenced debates about commercial governance in the critical middle decades of the seventeenth century, culminating in the attempt to create a national monopoly through the navigation acts, ‘securing sovereignty’ over the nation's trade. The second half of this article examines this in more detail with reference to the ideas of a prominent defender of the 1651 Navigation Act: Benjamin Worsley.