The subject of this essay is propria and their relation to essence. Propria, roughly characterized, are those real properties of a thing which are natural but nonessential to it, and which are said to “flow from” the thing’s essence, where this “flows from” relation is understood to designate a kind of explanatory relation. For example, it is said that Socrates’s risibility flows from his essential humanity; and it is said that salt’s solubility in water flows from the essential natures of both salt and water. The question I raise and attempt to answer in this essay is: In what sense do propria “flow from” essences? What kind of explanatory relation is this exactly? Some suggest that it is a relation of logical consequence (e.g., Kit Fine); others, of grounding (e.g., Michael Gorman); and still others, of formal causation (e.g., David Oderberg). In this essay, I reintroduce and defend a view suggested by the late scholastic Spanish philosopher and theologian Francisco Suárez, who in 1597 wrote that effluence is best understood as a very special kind of efficient causation, which we can call the relation of emanation. The thesis of this essay, then, is that propria emanate from essences. Along the way, this paper offers a new taxonomy of types of propria; it explains the significance of propria for the metaphysics and epistemology of essences; it discusses at length varieties of efficient causation (and emanation in particular); and then it offers an extensive abductive argument in favor of Suárez’s account, whereby the former accounts of effluence are critiqued, each in turn, and Suárez’s view is motivated and ultimately shown to be superior to its competitors.