Brennan's interests in Ancient Philosophy are fairly extensive: he has read and studied over the whole period, from Presocratics to Late Platonists. Most of his publications have come from the center of that period, specifically the Hellenistic era: Epicureans, Stoics, and Skeptics. But he has also published on the Presocratic Anaxagoras, and co-translated a long treatise written by Simplicius, one of the last non-christian Greek philosophers, probably around 530 A.D. Brennan has also published on Aristotle, especially his logical theories. Recently he has been working more on Plato, whom he considers by far the greatest and most interesting of all philosophers (ancient and modern). His topical interests center around ethics, but extend fairly far from that center. The study of ethics in antiquity is always closely linked to theories of psychology and intentional action, and these in turn to theories of epistemology and logic. Brennan has little taste for metaphysical questions narrowly considered, but show him how they make a difference to ethics or psychology and he is instantly avid for metaphysics. Although he has not published on any contemporary topics, and makes no effort to give his own work a specious allure to contemporary eyes, Brennan nevertheless enjoys discussing contemporary problems with colleagues and visitors, and likes to think that he's tolerably conversant with a range of recent controversies. He also thinks that 20th century analytical tools are indispensable for the study of ancient philosophy; this is especially the case with logic. Brennan is equally happy working with students who are interested in the history of philosophy per se, as he is, and students whose interest in historical figures or debates is largely instrumental. He is especially happy to be working with a group of colleagues who value and encourage both historical sensitivity and in-depth familiarity with current debates, and who work to foster both strengths in our students.