Sellars sits between the academic and trade audiences in a way that almost no other living Stoic writer does. He is a senior philosopher at Royal Holloway, London, with a doctoral background in Hellenistic ethics and a research focus on the ancient philosophical schools as traditions of practice. He is also, in Lessons in Stoicism and The Pocket Stoic, a writer of plain, careful, mentor-toned books that the new reader can finish in an afternoon without feeling either patronised or lectured at.
The 2006 Stoicism is the work scholars cite. It treats the school's logic, physics, and ethics in turn, with proper attention to the doxographical sources (Diogenes Laertius, Stobaeus, Cicero, Plutarch) and the fragments of the early Stoa. It is the book to recommend to a reader who wants to understand the system — Zeno through Chrysippus, Panaetius and Posidonius, into Roman Stoicism — rather than just the practical techniques.
His distinctive contribution to the modern revival is what Lessons in Stoicism names but does not over-name: that Stoicism is the philosophical tradition with the most explicit and developed account of philosophy as a way of life — a phrase he inherits from Pierre Hadot and uses without apology. Where some modern interpreters treat the practical techniques as detachable from the underlying metaphysics, Sellars takes the integrated view seriously: the exercises are pedagogically meaningful because they belong to a coherent picture of what a human life is for.
He is the modern Stoic to recommend to someone who wants neither a self-help book nor a graduate textbook — but a serious short introduction by a serious philosopher writing in plain English.