This article examines the sphere of ethics in the thought of the Dutch Calvinist statesman and theologian Abraham Kuyper. The first section establishes that Kuyper did consider ethics to be a sphere and what he believed it to be. The second section uses this outline of the sphere of ethics to elucidate the relationship between ethics and the state for Kuyper. It teases out three theses in Kuyper’s work: (1) Ethics and the scope of the state stand in inverse (or negative) relationship. (2) Ethics and legal advancement stand in direct (or positive) relationship. (3) Ethics needs the state to help facilitate its own development throughout society. Taken together, I argue that the spheres of ethics and the state thus stand in mutually dependent (or reciprocal) relationship to, rather than “hermetically sealed off” from, one another.