In the canon of ancient literature, where public genres — orations, national epics, and plays performed before thousands —predominate, it is the rare intimate or secretive voice that has most often captured the modern ear. The philosophic diary of Marcus Aurelius, known today as Meditations, commands the largest audience today among voluntary readers of the Classics (that is, those not compelled by instructors and syllabuses), and Augustine’s intensely personal Confessions is not far behind. In a landscape dominated by memoirs, blogs and other forms of self-revelation, these records of one individual’s thoughts feel reassuringly intimate and, for some, moving to a degree that can shift values — toward Marcus Aurelius’ sober Stoicism, or toward Augustine’s ardent Christianity.

Both Marcus and Augustine characterized their texts as private documents, not intended for the readers who have in fact relished them. Marcus called his writings Ta eis heauton, “Things for himself” in Greek, and may genuinely have thought that his collected reflections would never leave his imperial tent. Augustine’s book, as the title reveals, takes the form of an imagined act of confession, with God himself serving as priest and addressee. We do not read these men so much as overhear them; we intrude upon their solitude. Their revelations are more precious because they were never meant to be shared.

It was the Roman philosopher Seneca who pioneered this technique in his magnum opus, a work known by various titles: Moral Epistles, Letters to Lucilius, Letters from a Stoic, and now Letters on Ethics. Ostensibly a collection of missives written to a close friend, the Letters are in fact short philosophic essays directed broadly at Neronian Rome, a society where, in Seneca’s eyes at least, such instruction was badly needed. Like the Meditations that followed them a century later, they uphold the values of Stoicism, the Greek school of thought that sought happiness in a life of reason, service, and fidelity to a strict moral code. But like the Confessions of Augustine, the Letters are also, in part, an act of atonement. For Seneca had sins on his conscience, and the Letters, composed as he neared the end of a morally complex life, were, he knew, his last, best chance at redemption.

It seems that Seneca had ignored the injunctions of his great philosophic role model, Socrates, against the ambitions and distractions of politics. In his mid-thirties, already an accomplished author of moral treatises, he chose to enter the Roman senate. Later, after walking a twisting path that saw him exiled to Corsica and then recalled, he was appointed as tutor to the young Nero, heir apparent to Claudius (the emperor whom Robert Graves channeled in his famous historical novels). In 54 A.D., when Claudius died — most likely poisoned by his wife Agrippina to secure the throne for Nero, her son — Seneca found himself the most powerful man in the Roman empire, mentor to a volatile 16-year-old who had little interest in governance.

For more than a decade, Seneca maintained a double life that has puzzled historians and troubled readers of the Letters. From behind the palace scenes, he steered the Roman state and supervised damage control whenever Nero’s increasingly bizarre impulses led him to kill off members of the royal family or to don the delicate cloak and high boots of a Greek lyre player and give operatic concerts. But he continued writing all during this time, producing a vast body of moral treatises urging his readers toward virtue, the suppression of the passions, and the cultivation of the mind. Seldom in history has a philosopher’s message diverged so dramatically from his own ethical example, though recent revelations about the flirtations with Nazism of both Martin Heidegger and Paul de Man have perhaps provided modernity with parallel cases.

Proximity to Nero brought Seneca wealth as well as power. He became one of the richest men of his time, with estates, gardens and vineyards in many Roman provinces. His financial empire even extended to Rome’s newest acquisition, southern Britain, and contemporaries accused him of provoking a hugely destructive uprising there — Queen Boudicca’s revolt — by lending at interest and then abruptly calling in his debts. The charge may be groundless but, even so, it no doubt arose out of public resentment at Seneca’s aggressive growth strategies, a highly visible violation of the Stoic principles he avowed in his writings.

As Seneca reached his sixties and Nero his twenties, the costs of maintaining this double identity — multi-billionaire and chief minister to a willful autocrat, but author of essays that cast a cold eye on wealth and power — became inescapably clear. Political enemies spoke out loudly, decrying what they saw as arrogant hypocrisy. Nero became estranged, resentful of Seneca’s moral gravity, yet would not let the regime’s greatest personnel asset withdraw from court. By the time Seneca began the Letters, in 62 A.D., he had become persona non grata to Nero even though his request to leave the palace had been rejected, and threats had begun to loom, including (according to one Roman source) an attempt to have him poisoned.

Seneca might well have judged that the Letters, his longest and most far-reaching work, would be his last, best chance to address the Roman people. If so, he would have been right. In the Spring of 65 CE, only a few months after the latest datable letter, Seneca was implicated in an assassination plot and forced by Nero to commit suicide. As he opened his veins and waited for death to arrive, Seneca lamented to his friends that, because Nero had forbidden him to alter his will, he could only leave them his imago vitae, the template of his complex and bifurcated life. Nowhere is that template better preserved than in the 124 surviving Letters, and to read them today is to become a sharer in Seneca’s rich but complicated inheritance.

This month the Letters appear in the first complete English translation in many decades — since that of R.M. Gummere in the Loeb Classical Library, published between 1917 and 1925 — and the only one, to my knowledge, that includes annotations. The superb volume, by Margaret Graver and Tony Long, takes its place as the fifth installment of the Complete Works of Seneca series, an important project that debuted in 2010. The editorial team that designed the series — Chicagoans Elizabeth Asmis, Martha Nussbaum, and Shadi Bartsch — has thus far shown great judiciousness in assigning translators and editors the task of capturing the many voices in the broad Senecan corpus, and the whole series has been attractively packaged by the University of Chicago Press, with a wonderful introductory essay by the series editors at the front of each volume. Two final volumes will appear next year, comprising the tragedies generally assigned to Seneca (some questions still linger as to whether he wrote them) and the historical drama Octavia, now usually attributed to one of Seneca’s followers, a play that lists Seneca himself among its dramatis personae.

One of the self-professed goals of the series is “to restore Seneca’s oeuvre to the stature it enjoyed prior to the nineteenth century, and to introduce Seneca’s voice to a new generation of readers in philosophy, literature, drama, and the humanities” — a tall order, given how far that stature has declined. N-gram searches of Seneca’s name are vitiated by the fact that he shared a name with his father, another Roman writer whose work in part survives, but it’s fair to say that interest in Seneca the Younger has been declining for a very long time, despite the recent revival of Stoicism as a viable ethical system (spurred by authors like William Irvine, Tom Miles, and Admiral James Stockdale), and despite the interest Michel Foucault took in Seneca in the third volume of his History of Sexuality, published in English in 1986.

Graver and Long, in their introduction to the new edition of the Letters, date the high-water mark of Seneca’s influence to the 16th century, and regard the intervening half-millennium as a long downhill slide: “Some 18th-century authors…mention Seneca approvingly….but thereafter his influence declines. For the next two centuries, he largely drops out of general circulation and citation.” They offer no insight into why this is so, but the sheer multiplicity and diversity of Seneca’s works is no doubt part of the explanation. Montaigne and Erasmus, who similarly “contained multitudes” in their writings, admired and imitated Seneca, but modern readers have far preferred the less polyphonous Stoic treatises of Marcus Aurelius and Epictetus, from which ‘guides to life’ are more easily extracted. (On a recent visit to Yale around the time of commencement, I observed the Meditations prominently displayed on a table devoted to “Advice for Graduates;” one cannot imagine any of Seneca’s treatises, and especially not the Letters, occupying the same space, though unlike Marcus he sought quite earnestly to give moral instruction to the young.)

The sheer length of the Letters, as compared with the slender treatises of other Roman Stoics, has posed another problem for potential readers. In the epistolary format he invented, Seneca found a way to indulge his own prolixity without limit; he kept on adding to the collection right up until the time of his death, and the 124 letters we still possess, filling out three Loeb volumes, do not comprise the entire collection (at least two additional books have been lost in transmission). “It is impossible to read the Moral Epistles without fatigue,” wrote classicists Denis Henry and B. Walker in 1963, with an unguarded candor of the kind that is all too rare in scholarly writing. “The platitudes are so wan, so deficient in color, that is astonishing that anyone should have kept on writing them for so long.” Quintilian, in the Institutio Orataria, similarly finds fault with Seneca for failing to exercise authorial self-restraint. The great river of verbiage he produced in the last years of his life, to paraphrase what Callimachus once said of Homer, carried with it a fair amount of mud. For this reason, it must be said that, though the new Chicago translation of the Letters will find a place of honor on many bookshelves, most of those reading, or teaching, the work will be better served by an excerpted version, like those published in the Penguin Classics or Oxford World Classics series.

The latter volume presents a sensible selection comprising about two-thirds of the work, with notes by Elaine Fantham addressing a wide variety of historical, cultural and philosophic questions. Graver and Long, by contrast, focus their annotations on Seneca’s contributions to the philosophic debates of the Hellenistic schools; these comments, with their valuable cross-references to other ancient writers, will deeply interest intellectual historians and other scholars, but more general readers will sometimes crave a wider view of Seneca’s life and times. In Letter 8, for example, where Seneca seems to refer darkly to his political career under Nero, and the ill-fame it had brought him — ““I am committing to the page some healthful admonitions, like the recipe for useful salves. I have found these effective on my own sores, which, even if not completely healed, have ceased to spread” — these editors pass in silence over the peculiar metaphor, noting instead that “the speech that follows gives an initial statement of the core message of Stoic ethics.” In Letter 73, which many scholars have regarded as a crucial document concerning Seneca’s relations with the regime in which he served, Graver and Long again stick to the doctrinal and avoid the historical and biographical.

But no commentary can address all the manifold questions raised by the Letters, and perhaps it is better — especially in a work that seeks to put the entire work between a single set of covers — not to try. Graver and Long have at least dealt expertly with one aspect of the work, and have produced a sturdy, lively translation as well. This latest addition to the Complete Works of Seneca helps establish that series as a landmark event for readers of ancient philosophy, and underscores the loftier aspirations of an author who, all too often, failed to live up to his own ethical ideals.

James Romm is James H. Ottaway Jr. Professor of Classics at Bard College in Annandale, N.Y., and author of several books, including Dying Every Day: Seneca at the Court of Nero. He reviews regularly for the Wall Street Journal, the London Review of Books and the Times Literary Supplement.