Hierocles is a shadowy figure. We know almost nothing about his life. He flourished in the second century CE, probably under Hadrian or shortly after. His surviving work was effectively lost until H. von Arnim's 1906 edition of the Elements of Ethics — a Stoic ethical treatise on a papyrus (P.Berol. 9780) acquired in the 1890s from the Egyptian town of Hermopolis. The work is fragmentary but substantial enough to give us a clear sense of his system.
His enduring contribution to the tradition is the doctrine of oikeiōsis — usually translated as appropriation or affiliation or belonging — and its corollary, the concentric circles of concern. Oikeiōsis is the Stoic name for the natural impulse by which an animal recognizes its own well-being as its own and pursues it; in humans, the impulse extends, through reason, outward — first to one's own body, then to one's family, then to one's wider community, and ultimately to the whole of humanity. Each layer is a natural extension of the same original impulse, not an arbitrary altruistic add-on.
Hierocles' image: imagine yourself standing at the centre of a series of concentric circles. The innermost contains your own mind. The next contains your body. The next, your immediate family. The next, your extended family. The next, your neighbours and townspeople. The next, your countrymen. The outermost, the entire human race. The ethical project, he says, is to contract the outer circles toward the centre — to treat strangers more like neighbours, neighbours more like family, family more like oneself. The duty does not move outward through indifference and become weaker; it moves inward through practice and becomes more vivid.
This doctrine is the foundation of Stoic cosmopolitanism. It explains why the Stoics treat duty to humanity at large not as an exception to self-interest but as a continuous extension of it. And it gives the practical Stoic a working tool — when you find yourself indifferent to the suffering of distant people, the diagnosis is not lack of feeling. It is failure to contract the circle. The remedy is imaginative work: bring the distant case closer until the indifference no longer makes sense.
Hierocles is one of the few late-Stoic ethicists whose voice we can recover at all. He is also a corrective to the popular reduction of Stoicism to a philosophy of solitary resilience. The Stoic, by Hierocles' doctrine, owes the community his most demanding work — and the demand is rooted in the same nature that makes him care for his own body.